Hydrophobic and Hydrophilic Interactions
Capillary Electrochromatography
Glycomics
Chromatography, Reverse-Phase
Heparinoids
Tandem Mass Spectrometry
Wettability
Spectrometry, Mass, Electrospray Ionization
Polysaccharides
Mass Spectrometry
Chromatography, High Pressure Liquid
Chromatography
Reproducibility of Results
Glycosylation
Models, Molecular
Amino Acid Sequence
Molecular Sequence Data
Allosteric activation mechanism of the alpha 1 beta 2 gamma 2 gamma-aminobutyric acid type A receptor revealed by mutation of the conserved M2 leucine. (1/4501)
A conserved leucine residue in the midpoint of the second transmembrane domain (M2) of the ligand-activated ion channel family has been proposed to play an important role in receptor activation. In this study, we assessed the importance of this leucine in the activation of rat alpha 1 beta 2 gamma 2 GABA receptors expressed in Xenopus laevis oocytes by site-directed mutagenesis and two-electrode voltage clamp. The hydrophobic conserved M2 leucines in alpha1(L263), beta2(L259), and gamma 2(L274) subunits were mutated to the hydrophilic amino acid residue serine and coexpressed in all possible combinations with their wild-type and/or mutant counterparts. The mutation in any one subunit decreased the EC(50) and created spontaneous openings that were blocked by picrotoxin and, surprisingly, by the competitive antagonist bicuculline. The magnitudes of the shifts in GABA EC(50) and picrotoxin IC(50) as well as the degree of spontaneous openings were all correlated with the number of subunits carrying the leucine mutation. Simultaneous mutation of the GABA binding site (beta 2Y157S; increased the EC(50)) and the conserved M2 leucine (beta 2L259S; decreased the EC(50)) produced receptors with the predicted intermediate agonist sensitivity, indicating the two mutations affect binding and gating independently. The results are discussed in light of a proposed allosteric activation mechanism. (+info)Gamma-aminobutyric acid increases the water accessibility of M3 membrane-spanning segment residues in gamma-aminobutyric acid type A receptors. (2/4501)
Gamma-aminobutyric acid type A (GABA(A)) receptors are members of the ligand-gated ion channel gene superfamily. Using the substituted cysteine accessibility method, we investigated whether residues in the alpha(1)M3 membrane-spanning segment are water-accessible. Cysteine was substituted, one at a time, for each M3 residue from alpha(1)Ala(291) to alpha(1)Val(307). The ability of these mutants to react with the water-soluble, sulfhydryl-specific reagent pCMBS(-) was assayed electrophysiologically. Cysteines substituted for alpha(1)Ala(291) and alpha(1)Tyr(294) reacted with pCMBS(-) applied both in the presence and in the absence of GABA. Cysteines substituted for alpha(1)Phe(298), alpha(1)Ala(300), alpha(1)Leu(301), and alpha(1)Glu(303) only reacted with pCMBS(-) applied in the presence of GABA. We infer that the pCMBS(-) reactive residues are on the water-accessible surface of the protein and that GABA induces a conformational change that increases the water accessibility of the four M3 residues, possibly by inducing the formation of water-filled crevices that extend into the interior of the protein. Others have shown that mutations of alpha(1)Ala(291), a water-accessible residue, alter volatile anesthetic and ethanol potentiation of GABA-induced currents. Water-filled crevices penetrating into the interior of the membrane-spanning domain may allow anesthetics and alcohol to reach their binding sites and thus may have implications for the mechanisms of action of these agents. (+info)A numerical measure of amino acid residues similarity based on the analysis of their surroundings in natural protein sequences. (3/4501)
A measure of similarity between amino acid residues based on the analysis of the surroundings of each residue in primary structures of native proteins is proposed. The statistical data used for this purpose were obtained from the analysis of 168,808 protein sequences, which comprise the Protein Identification Research database (release 63). Using various threshold values of the proposed measure, amino acid residues were classified into several groups. The classification elaborated differs essentially from groupings previously used. The numerical measure of amino acid residues similarity can be used in site-directed mutagenesis studies for the prediction of probability of local spatial rearrangements in proteins. (+info)Sterically stabilized cationic liposomes improve the uptake and immunostimulatory activity of CpG oligonucleotides. (4/4501)
Immunostimulatory CpG oligonucleotides (ODN) show promise as immune adjuvants, anti-allergens, and immunoprotective agents. Increasing the bioavailability and duration of action of CpG ODN should improve their therapeutic utility. Encapsulating ODN in sterically stabilized cationic liposomes provides protection from serum nucleases while facilitating uptake by B cells, dendritic cells, and macrophages. In a pathogen challenge model, sterically stabilized cationic liposomes encapsulation doubled the duration of CpG ODN-induced immune protection. In an immunization model, coencapsulation of CpG ODN with protein Ag (OVA) magnified the resultant Ag-specific IFN-gamma and IgG responses by 15- to 40-fold compared with Ag plus CpG ODN alone. These findings support the use of sterically stabilized cationic liposomes to significantly enhance the therapeutic efficacy of CpG ODN. (+info)Role of interfacial hydrophobic residues in the stabilization of the leucine zipper structures of the transcription factors c-Fos and c-Jun. (5/4501)
This study documents a new and versatile experimental approach to study the relative stabilization energetics of recombinant polypeptide and protein mutants. In particular, the effect of temperature change over the range of T = 278-338 K on the thermodynamics of interaction of several leucine zipper coiled-coil polypeptides related to the transcription factors, c-Fos and c-Jun, following binding to immobilized n-octyl ligands has been determined. Plots of the change in heat capacity, DeltaC(p)0, versus T, in combination with the corresponding van't Hoff plots, allow the energetics of the interaction of polypeptides with n-octyl ligands to be rationalized and the respective mid-point transition temperatures, T(m) values, determined for the melting of their supramolecular structures. The derived experimental data correlated well with information available from other procedures, confirming that this new approach provides complementary insight into the interaction thermodynamics and the molecular nature of the thermal stability of recombinant polypeptides in non-polar or other types of chemical environments. (+info)Bile-salt hydrophobicity is a key factor regulating rat liver plasma-membrane communication: relation to bilayer structure, fluidity and transporter expression and function. (6/4501)
Bile-salt hydrophobicity regulates biliary phospholipid secretion and subselection. The aim of this study was to determine whether bile salts can influence liver plasma membrane phospholipids and fluidity in relation to the ATP-dependent transporter. Rats were depleted of bile salts by overnight biliary diversion and then sodium taurocholate was infused intravenously at a constant rate (200 nmol/min per 100 g of body weight), followed by infusion of bile salts with various hydrophobicities (taurochenodeoxycholate, tauroursodeoxycholate, tauro-beta-muricholate, tauro-alpha-muricholate at 200 nmol/min per 100 g of body weight). The hydrophobicity of the infused bile salts correlated with that of biliary phospholipids, but was inversely related to that of the canalicular membrane bilayer. Canalicular membrane fluidity (estimated by 1,6-diphenyl-1,3,5-hexatriene fluorescence depolarization) and expression of multidrug-resistance proteins (Mrp2, Mrp3) and apical Na(+)-dependent bile-salt transporter (ASBT) were increased by hydrophilic bile salts, although there was no marked change in the expression of P-glycoprotein subfamilies (Mdr2). Bile-salt export pump (Bsep) expression was increased along with increasing bile-salt hydrophobicity. Bile salts modulate canalicular membrane phospholipids and membrane fluidity, as well as the ATP-dependent transporter expression and function, and these actions are associated with their hydrophobicity. The cytoprotective effect of hydrophilic bile salts seems to be associated with induction of Mrp2, Mrp3 and ASBT. (+info)Structure-function analysis of the heat shock factor-binding protein reveals a protein composed solely of a highly conserved and dynamic coiled-coil trimerization domain. (7/4501)
Heat shock factor-binding protein (HSBP) 1 is a small, evolutionarily conserved protein originally identified in a yeast two-hybrid screen using the trimerization domain of heat shock factor (HSF) 1 as the bait. Similar in size to HSF1 trimerization domain, human HSBP1 contains two arrays of hydrophobic heptad repeats (designated HR-N and HR-C) characteristic of coiled-coil proteins. Proteins of the HSBP family are relatively small (<100 residues), comprising solely a putative coiled-coil oligomerization domain without any other readily recognizable structural or functional motif. Our biophysical and biochemical characterization of human HSBP1 reveals a cooperatively folded protein with high alpha-helical content and moderate stability. NMR analyses reveal a single continuous helix encompassing both HR-N and HR-C in the highly conserved central region, whereas the less conserved carboxyl terminus is unstructured and accessible to proteases. Unlike previously characterized coiled-coils, backbone 15N relaxation measurements implicate motional processes on the millisecond time scale in the coiled-coil region. Analytical ultracentrifugation and native PAGE studies indicate that HSBP1 is predominantly trimeric over a wide concentration range. NMR analyses suggest a rotationally symmetric trimer. Because the highly conserved hydrophobic heptad repeats extend over 60% of HSBP1, we propose that HSBP most likely regulates the function of other proteins through coiled-coil interactions. (+info)Optimization of microbial specificity in cyclic peptides by modulation of hydrophobicity within a defined structural framework. (8/4501)
In the present study we have utilized the structural framework of the analog GS14K4 (cyclo(VKLd-KVd-YPL KVKLd-YP, where d denotes a d-amino acid)), to examine the role of hydrophobicity in microbial activity and specificity. The hydrophobicity of GS14K4 was systematically altered by residue replacements in the hydrophobic sites of the molecule to produce a series of analogs that were either less or more hydrophobic than the parent compound. Circular dichroism spectroscopy and reversed-phase high performance liquid chromatography analysis showed that the molecules were structurally similar and only differed in overall hydrophobicity. The hydrophobicity of GS14K4 was found to be the midpoint for hemolytic activity, with more hydrophobic analogs exhibiting increased hemolytic activity and less hydrophobic analogs showing decreased hemolytic activity. For antimicrobial activity there were differences between the hydrophobicity requirements against Gram-positive and Gram-negative microorganisms. The hydrophobicity of GS14K4 was sufficient for maximum activity against Gram-negative microorganisms and yeast, with no further increases in activity occurring with increasing hydrophobicity. With Gram-positive microorganisms significant increases in activity with increasing hydrophobicity were seen in three of the six microorganisms tested. A therapeutic index (calculated as a measure of specificity of the peptides for the microorganisms over human erythrocytes) served to define the boundaries of a therapeutic window within which lay the optimum peptide hydrophobicity for each microorganism. The therapeutic window was found to be at a lower hydrophobicity level for Gram-negative microorganisms than for Gram-positive microorganisms, although the limits were more variable for the latter. Our results show that the balance between activity and specificity in the present cyclic peptides can be optimized for each microorganism by systematic modulation of hydrophobicity. (+info)Hydrophobic interactions: These are the interactions that occur between non-polar molecules or groups of atoms in an aqueous environment, leading to their association or aggregation. The term "hydrophobic" means "water-fearing" and describes the tendency of non-polar substances to repel water. When non-polar molecules or groups are placed in water, they tend to clump together to minimize contact with the polar water molecules. These interactions are primarily driven by the entropy increase of the system as a whole, rather than energy minimization. Hydrophobic interactions play crucial roles in various biological processes, such as protein folding, membrane formation, and molecular self-assembly.
Hydrophilic interactions: These are the interactions that occur between polar molecules or groups of atoms and water molecules. The term "hydrophilic" means "water-loving" and describes the attraction of polar substances to water. When polar molecules or groups are placed in water, they can form hydrogen bonds with the surrounding water molecules, which helps solvate them. Hydrophilic interactions contribute to the stability and functionality of various biological systems, such as protein structure, ion transport across membranes, and enzyme catalysis.
Capillary electrochromatography (CEC) is a separation technique that combines the principles of capillary electrophoresis and high-performance liquid chromatography (HPLC). In CEC, an electric field is applied to a liquid flowing through a narrow fused-silica capillary tube packed with a stationary phase.
The analytes (the substances being separated) are carried by the electroosmotic flow of the liquid and interact with the stationary phase as they migrate through the capillary, resulting in separation based on both charge and size/hydrophobicity. CEC offers high efficiency, resolution, and sensitivity for the separation of a wide range of analytes, including small molecules, peptides, proteins, and nucleic acids.
The medical definition of Capillary Electrochromatography is not commonly used as it is primarily employed in research settings for the analysis of various biological samples, pharmaceuticals, and environmental pollutants.
Liquid chromatography (LC) is a type of chromatography technique used to separate, identify, and quantify the components in a mixture. In this method, the sample mixture is dissolved in a liquid solvent (the mobile phase) and then passed through a stationary phase, which can be a solid or a liquid that is held in place by a solid support.
The components of the mixture interact differently with the stationary phase and the mobile phase, causing them to separate as they move through the system. The separated components are then detected and measured using various detection techniques, such as ultraviolet (UV) absorbance or mass spectrometry.
Liquid chromatography is widely used in many areas of science and medicine, including drug development, environmental analysis, food safety testing, and clinical diagnostics. It can be used to separate and analyze a wide range of compounds, from small molecules like drugs and metabolites to large biomolecules like proteins and nucleic acids.
Glycomics is the study of the glycome, which refers to the complete set of carbohydrates or sugars (glycans) found on the surface of cells and in various biological fluids. Glycomics encompasses the identification, characterization, and functional analysis of these complex carbohydrate structures and their interactions with other molecules, such as proteins and lipids.
Glycans play crucial roles in many biological processes, including cell-cell recognition, signaling, immune response, development, and disease progression. The study of glycomics has implications for understanding the molecular basis of diseases like cancer, diabetes, and infectious disorders, as well as for developing novel diagnostic tools and therapeutic strategies.
Reverse-phase chromatography is a type of liquid chromatography that is commonly used in analytical chemistry and biochemistry to separate, identify, and purify complex mixtures of chemicals or biological molecules. In this technique, the stationary phase is a nonpolar solid, such as octadecyl silica (ODS) or C18, which is coated with a polar solvent, while the mobile phase is a nonpolar solvent, such as methanol or acetonitrile.
The term "reverse-phase" refers to the fact that the polarity of the stationary and mobile phases is reversed compared to normal-phase chromatography. In normal-phase chromatography, the stationary phase is polar and the mobile phase is nonpolar, which results in the separation of analytes based on their polarity. However, in reverse-phase chromatography, the stationary phase is nonpolar and the mobile phase is polar, which means that the separation of analytes is based on their hydrophobicity or hydrophilicity.
In reverse-phase chromatography, hydrophobic molecules elute more slowly than hydrophilic molecules because they have a stronger affinity for the nonpolar stationary phase. The retention time of an analyte can be adjusted by changing the composition of the mobile phase or the pH of the solution. This technique is widely used in the analysis of drugs, metabolites, peptides, proteins, and other biological molecules.
Acetonitrile is an organic compound with the formula CH3CN. It is a colorless liquid that is used as a solvent and in the production of various chemicals. Acetonitrile is weakly basic and polar, and it has a unique smell that is often described as unpleasant or sweet.
Acetonitrile is not considered to be a medication or a drug, so it does not have a medical definition. However, it is sometimes used in the medical field as a solvent for various applications, such as in the preparation of pharmaceutical products or in laboratory research. It is important to handle acetonitrile with care, as it can be harmful if swallowed, inhaled, or contacted with the skin.
Heparinoids are a group of substances that have similar properties to heparin, a highly sulfated glycosaminoglycan found in mast cells and basophils. Heparin is a powerful anticoagulant that works by accelerating the action of an enzyme called antithrombin III, which inhibits the formation of blood clots.
Heparinoids are often used as alternative anticoagulants to heparin in clinical settings. They have similar mechanisms of action and can also inhibit the coagulation cascade, preventing the formation of blood clots. However, heparinoids have a lower anticoagulant activity than heparin and may have different side effect profiles.
Examples of heparinoids include low molecular weight heparins (LMWHs), fondaparinux, and danaparoid. LMWHs are derived from standard heparin by chemical or enzymatic depolymerization and have a lower molecular weight than heparin. They have a more predictable anticoagulant response and longer half-life than standard heparin, making them useful for outpatient treatment of deep vein thrombosis and pulmonary embolism.
Fondaparinux is a synthetic pentasaccharide that selectively binds to antithrombin III and enhances its inhibitory activity against factor Xa, a key enzyme in the coagulation cascade. It has a long half-life and predictable pharmacokinetics, making it useful for the prevention and treatment of venous thromboembolism.
Danaparoid is a mixture of heparan sulfate, dermatan sulfate, and chondroitin sulfate derived from pig intestinal mucosa. It has a lower anticoagulant activity than heparin but a longer half-life and less frequent dosing requirements. Danaparoid is used for the prevention and treatment of venous thromboembolism, as well as for the management of heparin-induced thrombocytopenia (HIT), a rare but serious complication of heparin therapy.
Tandem mass spectrometry (MS/MS) is a technique used to identify and quantify specific molecules, such as proteins or metabolites, within complex mixtures. This method uses two or more sequential mass analyzers to first separate ions based on their mass-to-charge ratio and then further fragment the selected ions into smaller pieces for additional analysis. The fragmentation patterns generated in MS/MS experiments can be used to determine the structure and identity of the original molecule, making it a powerful tool in various fields such as proteomics, metabolomics, and forensic science.
"Wettability" is not a term that has a specific medical definition. It is a term that is more commonly used in the fields of chemistry, physics, and materials science to describe how well a liquid spreads on a solid surface. In other words, it refers to the ability of a liquid to maintain contact with a solid surface, which can have implications for various medical applications such as the design of medical devices or the study of biological surfaces. However, it is not a term that would typically be used in a clinical medical context.
Mass spectrometry with electrospray ionization (ESI-MS) is an analytical technique used to identify and quantify chemical species in a sample based on the mass-to-charge ratio of charged particles. In ESI-MS, analytes are ionized through the use of an electrospray, where a liquid sample is introduced through a metal capillary needle at high voltage, creating an aerosol of charged droplets. As the solvent evaporates, the analyte molecules become charged and can be directed into a mass spectrometer for analysis.
ESI-MS is particularly useful for the analysis of large biomolecules such as proteins, peptides, and nucleic acids, due to its ability to gently ionize these species without fragmentation. The technique provides information about the molecular weight and charge state of the analytes, which can be used to infer their identity and structure. Additionally, ESI-MS can be interfaced with separation techniques such as liquid chromatography (LC) for further purification and characterization of complex samples.
Polysaccharides are complex carbohydrates consisting of long chains of monosaccharide units (simple sugars) bonded together by glycosidic linkages. They can be classified based on the type of monosaccharides and the nature of the bonds that connect them.
Polysaccharides have various functions in living organisms. For example, starch and glycogen serve as energy storage molecules in plants and animals, respectively. Cellulose provides structural support in plants, while chitin is a key component of fungal cell walls and arthropod exoskeletons.
Some polysaccharides also have important roles in the human body, such as being part of the extracellular matrix (e.g., hyaluronic acid) or acting as blood group antigens (e.g., ABO blood group substances).
Mass spectrometry (MS) is an analytical technique used to identify and quantify the chemical components of a mixture or compound. It works by ionizing the sample, generating charged molecules or fragments, and then measuring their mass-to-charge ratio in a vacuum. The resulting mass spectrum provides information about the molecular weight and structure of the analytes, allowing for identification and characterization.
In simpler terms, mass spectrometry is a method used to determine what chemicals are present in a sample and in what quantities, by converting the chemicals into ions, measuring their masses, and generating a spectrum that shows the relative abundances of each ion type.
High-performance liquid chromatography (HPLC) is a type of chromatography that separates and analyzes compounds based on their interactions with a stationary phase and a mobile phase under high pressure. The mobile phase, which can be a gas or liquid, carries the sample mixture through a column containing the stationary phase.
In HPLC, the mobile phase is a liquid, and it is pumped through the column at high pressures (up to several hundred atmospheres) to achieve faster separation times and better resolution than other types of liquid chromatography. The stationary phase can be a solid or a liquid supported on a solid, and it interacts differently with each component in the sample mixture, causing them to separate as they travel through the column.
HPLC is widely used in analytical chemistry, pharmaceuticals, biotechnology, and other fields to separate, identify, and quantify compounds present in complex mixtures. It can be used to analyze a wide range of substances, including drugs, hormones, vitamins, pigments, flavors, and pollutants. HPLC is also used in the preparation of pure samples for further study or use.
Chromatography is a technique used in analytical chemistry for the separation, identification, and quantification of the components of a mixture. It is based on the differential distribution of the components of a mixture between a stationary phase and a mobile phase. The stationary phase can be a solid or liquid, while the mobile phase is a gas, liquid, or supercritical fluid that moves through the stationary phase carrying the sample components.
The interaction between the sample components and the stationary and mobile phases determines how quickly each component will move through the system. Components that interact more strongly with the stationary phase will move more slowly than those that interact more strongly with the mobile phase. This difference in migration rates allows for the separation of the components, which can then be detected and quantified.
There are many different types of chromatography, including paper chromatography, thin-layer chromatography (TLC), gas chromatography (GC), liquid chromatography (LC), and high-performance liquid chromatography (HPLC). Each type has its own strengths and weaknesses, and is best suited for specific applications.
In summary, chromatography is a powerful analytical technique used to separate, identify, and quantify the components of a mixture based on their differential distribution between a stationary phase and a mobile phase.
Reproducibility of results in a medical context refers to the ability to obtain consistent and comparable findings when a particular experiment or study is repeated, either by the same researcher or by different researchers, following the same experimental protocol. It is an essential principle in scientific research that helps to ensure the validity and reliability of research findings.
In medical research, reproducibility of results is crucial for establishing the effectiveness and safety of new treatments, interventions, or diagnostic tools. It involves conducting well-designed studies with adequate sample sizes, appropriate statistical analyses, and transparent reporting of methods and findings to allow other researchers to replicate the study and confirm or refute the results.
The lack of reproducibility in medical research has become a significant concern in recent years, as several high-profile studies have failed to produce consistent findings when replicated by other researchers. This has led to increased scrutiny of research practices and a call for greater transparency, rigor, and standardization in the conduct and reporting of medical research.
Glycosylation is the enzymatic process of adding a sugar group, or glycan, to a protein, lipid, or other organic molecule. This post-translational modification plays a crucial role in modulating various biological functions, such as protein stability, trafficking, and ligand binding. The structure and composition of the attached glycans can significantly influence the functional properties of the modified molecule, contributing to cell-cell recognition, signal transduction, and immune response regulation. Abnormal glycosylation patterns have been implicated in several disease states, including cancer, diabetes, and neurodegenerative disorders.
Proteomics is the large-scale study and analysis of proteins, including their structures, functions, interactions, modifications, and abundance, in a given cell, tissue, or organism. It involves the identification and quantification of all expressed proteins in a biological sample, as well as the characterization of post-translational modifications, protein-protein interactions, and functional pathways. Proteomics can provide valuable insights into various biological processes, diseases, and drug responses, and has applications in basic research, biomedicine, and clinical diagnostics. The field combines various techniques from molecular biology, chemistry, physics, and bioinformatics to study proteins at a systems level.
Molecular models are three-dimensional representations of molecular structures that are used in the field of molecular biology and chemistry to visualize and understand the spatial arrangement of atoms and bonds within a molecule. These models can be physical or computer-generated and allow researchers to study the shape, size, and behavior of molecules, which is crucial for understanding their function and interactions with other molecules.
Physical molecular models are often made up of balls (representing atoms) connected by rods or sticks (representing bonds). These models can be constructed manually using materials such as plastic or wooden balls and rods, or they can be created using 3D printing technology.
Computer-generated molecular models, on the other hand, are created using specialized software that allows researchers to visualize and manipulate molecular structures in three dimensions. These models can be used to simulate molecular interactions, predict molecular behavior, and design new drugs or chemicals with specific properties. Overall, molecular models play a critical role in advancing our understanding of molecular structures and their functions.
An amino acid sequence is the specific order of amino acids in a protein or peptide molecule, formed by the linking of the amino group (-NH2) of one amino acid to the carboxyl group (-COOH) of another amino acid through a peptide bond. The sequence is determined by the genetic code and is unique to each type of protein or peptide. It plays a crucial role in determining the three-dimensional structure and function of proteins.
Molecular sequence data refers to the specific arrangement of molecules, most commonly nucleotides in DNA or RNA, or amino acids in proteins, that make up a biological macromolecule. This data is generated through laboratory techniques such as sequencing, and provides information about the exact order of the constituent molecules. This data is crucial in various fields of biology, including genetics, evolution, and molecular biology, allowing for comparisons between different organisms, identification of genetic variations, and studies of gene function and regulation.
Phoratoxin and viscotoxin
Biosynthesis
O-GlcNAc
Protein aggregation
Cell membrane
Langmuir-Blodgett film
Plant lipid transfer proteins
Essential fatty acid interactions
Protein metabolism
Micellar liquid chromatography
Polymer-protein hybrid
Stimuli-responsive drug delivery systems
Noncovalent solid-phase organic synthesis
Hydrogel dressing
Protein L
Nanogel
Micelle
Antimicrobial polymer
Hydrophilicity plot
Arieh Ben-Naim
Mesoporous organosilica
Type II secretion system
Wetting
Hormone receptor
Biomolecule
Janus particles
Hyperpolarization (physics)
Leucine-rich repeat
Angel food cake
Easy Cheese
Surfactin
Surface chemistry of cooking
An integrated approach to understanding the sorption mechanism of phenanthrene by cork
Titratable transmembrane residues and a hydrophobic plug are essential for manganese import via the Bacillus anthracis ABC...
Phoratoxin and viscotoxin - Wikipedia
Comprehensive structural analysis reveals broad-spectrum neutralizing antibodies against SARS-CoV-2 Omicron variants | Cell...
Molecules | Free Full-Text | Comparative Interaction Studies of Quercetin with 2-Hydroxyl-propyl-β-cyclodextrin and 2,6...
A Review on Nanofluids: Preparation, Stability Mechanisms, and Applications
Publications | Max Planck Institute of Colloids and Interfaces
NUCLEODUR PolarTec-HPLC columns-MACHEREY-NAGEL | MACHEREY-NAGEL
ncRNA | Free Full-Text | Common Features in lncRNA Annotation and Classification: A Survey
Novel Swine Influenza Virus Subtype H3N1, United States - Volume 12, Number 5-May 2006 - Emerging Infectious Diseases journal -...
NUCLEODUR PolarTec-UHPLC columns-MACHEREY-NAGEL | MACHEREY-NAGEL
Bioreactor mechanically guided 3D mesenchymal stem cell chondrogenesis using a biocompatible novel thermo-reversible...
Interactions between charged polypeptides and nonionic surfactants<...
Angel food cake - Wikipedia
The Rise and Fall of the Hydrophobic Effect in Protein Folding and Protein-Protein Association, and Molecular Recognition
An invisible interface
LU TP 96-28
Lectins: Sambucus Nigra Lectin (SNA, EBL), Agarose bound
Compound Purification | Universität Tübingen
In vivo uptake and cellular distribution of gold nanoshells in a preclinical model of xenografted human renal cancer | Gold...
Surface characterization
Publikationen | Technische Universität Ilmenau
Microrheology of giant-micelle solutions | EPL
Publications - Institute for Bioengineering of Catalonia
"Hydrophobic Hydration and Aggregation in Aqueous Solutions" by Joshua A. Long
Monomer Of Protein - Science Trends
Program for Monday, August 29th
Description: Characterisation and differentiation of kinase binding pockets in PKA and PIM1 by small molecule fragments using...
Electrode design paves way for better biofuel cells, electrochemical devices
Residues7
- Modeling suggests that access to these titratable residues is blocked by a ladder of hydrophobic residues, and ATP-driven conformational changes open and close this hydrophobic seal to permit metal binding and release. (nih.gov)
- The conservation of this arrangement of titratable and hydrophobic residues among ABC transporters of transition metals suggests a common mechanism. (nih.gov)
- The influence of molecular characteristics on the mutual interaction between peptides and nonionic surfactants has been investigated by studying the effects of surfactants on amphiphilic, random copolymers of alpha-L-amino acids containing lysine residues as the hydrophilic parts. (lu.se)
- The hydrophobic residues were either phenylalanine or tyrosine. (lu.se)
- The model has only two types of residues, hydrophobic and hydrophilic. (lu.se)
- Docking studies with these compounds against cyclooxygenase-2 receptor(PDB 1D: 1PXX) indicated that they exhibit specific interactions with key residues located in the site of the COX2 structure, which corroborates the hypothesis that these molecules are potential ligands of COX2. (ias.ac.in)
- In solution, compstatin forms a β-turn at residues Gln-5-Gly-8 with the disulfide bridge Cys-2-Cys-12, residues Ile-1-Val-4 and Thr-13 forming a hydrophobic cluster (PCT Pub. (justia.com)
Ionic4
- Versatile chromatography systems are available to separate compounds by hydrophobic, hydrophilic or ionic interactions, also by special affinity chromatography or size exclusion. (uni-tuebingen.de)
- It was found that predominantly hydrophobic interactions together with ionic/hydrophilic interactions between 12-2-12 Gemini surfactant and the saccharides maltodextrin and lactose play a role. (degruyter.com)
- A systematic study of the effects of hydrophilic ionic liquids concentration and nature (alkyl chain length and type of anion) on the activity of Candida antarctica lipase B is here reported. (ua.pt)
- This behavior is partially due to the ionic liquid impact on the thermodynamic water activity, but direct interactions between the hydrophilic ionic liquid and the enzyme are also disclosed. (ua.pt)
Hydrophobicity1
- However, a certain degree of peptide hydrophobicity is necessary to obtain an interaction with nonionic surfactant. (lu.se)
Nanoparticles3
- It achieved unprecedented mass loading of hydrophilic enzyme and hydrophobic/conductive metal nanoparticles and greatly increased electron transfer efficiency and current density. (phys.org)
- Amphiphilic assembled multilayers composed of glucose oxidases in aqueous media and hydrophobic/conductive nanoparticles in nonpolar media were deposited onto cotton fiber/textile to form the anode, which has notably increased electron transfer efficiency and immobilization stability. (phys.org)
- To mitigate the high fouling propensities of hydrophobic MD membranes while retaining their high salt rejection efficiencies, superhydrophobic poly-vinylidene fluoride (PVDF) nanofibre membranes embedded with silanized silica nanoparticles (f-SiO(2)NPs) were synthesised and coated with a hydrophilic active layer containing silver nanoparticles and carboxylated multi-walled carbon nanotubes (AgNPs/f-MWCNTs). (ugent.be)
Micelles via2
- Therefore, the peptide-surfactant complex is best described in terms of a necklace model, with the peptide interacting primarily with the palisade region of the micelles via its hydrophobic side chains. (lu.se)
- 2 Proteins are incorporated into these micelles via hydrophobic interactions. (sigmaaldrich.com)
Membrane10
- 1 These integral membrane proteins (IMPs) ( Figure 2 ) are not soluble in aqueous solutions as they aggregate to protect their hydrophobic domains, but are soluble in detergent solutions as micelles formed by detergents are analogous to the bilayers of the biological membranes. (sigmaaldrich.com)
- Hydrophobic regions of membrane proteins, normally embedded in the membrane lipid bilayer, are now surrounded by a layer of detergent molecules and the hydrophilic regions are exposed to the aqueous medium. (sigmaaldrich.com)
- Complete removal of detergent could result in aggregation due to the clustering of hydrophobic regions and, hence, may cause precipitation of membrane proteins. (sigmaaldrich.com)
- Superhydrophobic PVDF nanofibre membranes coated with an organic fouling resistant hydrophilic active layer for direct-contact membrane distillation," COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS , vol. 575, pp. 363-372, 2019. (ugent.be)
- This article discusses a Sartobind phenyl membrane adsorber that has been developed for the manufacturing-scale production of biomolecules based on hydrophobic interaction chromatography (HIC) principles. (biopharminternational.com)
- In addition to positively charged membranes, hydrophobic interaction membrane chromatography (HIC) has been described for the purification of a humanized MAb. (biopharminternational.com)
- The hydrophobic membrane adsorber is based on hydrophilic regenerated stabilized cellulose with hydrophobic phenyl groups covalently attached to the base matrix. (biopharminternational.com)
- Solute carriers (SLCs) are membrane transport proteins tasked with mediating passage of hydrophilic molecules across lipid bilayers. (duke.edu)
- We construct 3M™ LifeASSURE™ PSN Series filter capsules with high efficiency, naturally hydrophilic, Nylon 6,6 membrane. (3m.com)
- Another benefit our Nylon 6,6 membrane offers is a reduction for potential microbubble formation by not de-wetting in outgassing fluids unlike hydrophobic membranes such as polypropylene, UPE, and PTFE. (3m.com)
Membranes1
- Biological membranes consist of phospholipids that contain two hydrophobic groups connected to a polar head. (sigmaaldrich.com)
Adsorption4
- This result justifies the observed correlations as dichloromethane extractives, being hydrophobic, compete with phenanthrene adsorption, whereas phenolic groups, as well as negatively charged groups, enhance the hydrophilic character of the sorbent surface, thus hindering the adsorption of phenanthrene. (nih.gov)
- The non-specific adsorption of blood proteins on nanorobot surfaces could lead to clinical difficulties such as thrombosis and unwanted protein-mediated recognition interactions such as cell-nanorobot and nanorobot-nanorobot adhesion (aggregation). (nanomedicine.com)
- Various hydrophilic adsorbed coatings have been attached to artificial surfaces to make them more protein-resistant, in effect "passivating" them against protein adsorption and greatly reducing or preventing cell adhesion to biomedical implants [ 754 ]. (nanomedicine.com)
- f-SiO2 NPs-modified PVDF nanofibres showed the highest flux decline (82% after 60 h) associated with BSA adsorption induced by favourable hydrophobic-hydrophobic interactions. (ugent.be)
Lipid bilayers1
- This molecular architecture allows phospholipids to assemble as lipid bilayers in which the hydrophobic chains face each other while the polar head groups face outward to the aqueous milieu ( Figure 1 ). (sigmaaldrich.com)
Cellulose1
- Hydrophilic konjac glucomannan (KGM)/hydrophobic ethyl cellulose (EC) film was prepared in the ethanol/water environment. (bvsalud.org)
Molecular5
- Two approaches were integrated to reach this objective: (1) statistical multivariate analysis to obtain correlations between the sorption capacity, measured as K(oc), and the sorbent properties (i.e. polarity, acidic functional groups, %dichloromethane extractives, %ethanol and water extractives, %suberin, %lignin and %holocellulose) and (2) modeling calculations to obtain information on interaction at the molecular level. (nih.gov)
- A. Ben-Naim, "The Rise and Fall of the Hydrophobic Effect in Protein Folding and Protein-Protein Association, and Molecular Recognition," Open Journal of Biophysics , Vol. 1 No. 1, 2011, pp. 1-7. (scirp.org)
- A. Ben-Naim, "Molecular Theory of Water and Aqueous Solutions," Part II: Hydrophilic Effects in Protein Folding, Self-Assembly and Molecular Recognition," World Scientific, Singapore, 2011. (scirp.org)
- The film-forming solution and film properties were both characterized to analyze the molecular interaction changes. (bvsalud.org)
- The changing trend of mechanical properties and the FTIR results suggested that both ethanol content and ethanol evaporation impacted the molecular interaction during the film formation. (bvsalud.org)
Aggregation3
- Here, we use Raman spectroscopy combined with multivariate curve resolution (Raman-MCR), partial molar volume, and fluorescence spectroscopic methods to detect and quantify changes in hydration extent and structure due to hydrophobic aggregation and hydrophobic cavity structure. (purdue.edu)
- This hydration-shell spectrum therefore contains evidence of hydrophobic aggregation by changes in the solute vibrational features as well as information on the extent and structure of water perturbed in the hydration shell of the solute. (purdue.edu)
- Consequently, it will usually be desirable to suppress non-specific adhesive interactions involving individual physically-unlinked nanorobots, in order to permit unfettered nanorobot mobility and freedom of action within the human body and avoid particle aggregation. (nanomedicine.com)
Phenylalanine1
- Phenylalanine and leucine are both hydrophobic, however phenylalanine is large, aromatic and strand-preferring, while leucine is medium in size and prefers to be in a helix. (wikipedia.org)
Waals2
- This inorganic phosphate ion increases the toxin stability by neutralizing the positively charged basic amino acids of the monomers, creating possibilities for more Van Der Waals interactions. (wikipedia.org)
- Separation mechanism based on hydrophobic (van der Waals) and polar interactions. (mn-net.com)
Aggregates2
- The aggregates are hydrophobic and hydrophilic dimers, joined by intermolecular interaction. (wikipedia.org)
- Open questions remain regarding the degree of water restructuring in hydrophobic cavities, the extent of hydration in self-assembled aggregates, and the influence of water restructuring on hydrophobic interactions. (purdue.edu)
Chemistry1
- Water mediated hydrophilic and hydrophobic interactions are important for biological systems, atmospheric, geological, and environmental chemistry, and pharmaceuticals formulation development. (purdue.edu)
Enzyme1
- Cations with longer alkyl chains decrease the enzyme activity by obstruction of its non-polar active site, while direct interactions established between the enzyme and the anions, dominated by dispersion forces and hydrogen-bonding, contribute also for the loss of activity observed. (ua.pt)
Polar3
- Based on high-purity NUCLEODUR silica gel, a polar group was embedded in a hydrophobic C18. (mn-net.com)
- On montmorillonite, an ion exchange reaction of Lys side groups against alkali ions as well as interactions between alkali cations and polar groups in the peptide are explained. (aps.org)
- 2002). Mutational studies showed that the polar 3-turn and the hydrophobic cluster are essential for the inhibitory activity of compstatin (Furlong et al. (justia.com)
Hydrogen1
- The attractive supramolecular interactions (hydrogen bonding, interactions, and hydrophobic effects) drive the monomers to assemble, while opposed by repulsive electrostatic interactions that resist polymerisation. (europa.eu)
Separation1
- In related experiments, we are examining hydrophobic and hydrophilic interactions between water and various other materials using thermal desorption and surface spectroscopic techniques to probe interphase transport and phase separation. (pnnl.gov)
Chromatography1
- 16 Hydrophobic interaction is listed among the most commonly used chromatography methods for protein purification. (biopharminternational.com)
Proteins4
- By including sequence independent local interactions, which qualitatively reproduce local properties of functional proteins, the dominance of a native state for many sequences is observed. (lu.se)
- You can use the SurPASS 3 surface zeta potential analyzer to study the interaction of proteins in solution with the implant material. (anton-paar.com)
- In addition, several proteins that are not previously linked with blood-biomaterial interaction are presented and discussed. (ibecbarcelona.eu)
- Proteins are held in the lipid bilayer by hydrophobic interactions between the lipid tails and hydrophobic protein domains. (sigmaaldrich.com)
Protein5
- Since both of these amino acids are also hydrophobic this mutation is thought to have little interference with the folding and stability of the protein. (wikipedia.org)
- The interactions also offered simple and straightforward answers to the problems of protein folding, and protein-protein association. (scirp.org)
- Nevertheless, three striking differences were detected in the ATP-binding pocket, which influences protein-ligand interactions. (uni-marburg.de)
- In comparison with already published PKA and Pim1 binders, we could detect either known but also new structural scaffolds for the interactions with the protein. (uni-marburg.de)
- Our results suggest that a screening approach using protein crystallography is particularly useful to identify universal fragments for the conserved hydrophilic recognition sites found in target families such as SH2 domains, phosphatases, kinases, proteases, and esterases. (rcsb.org)
Electron3
- The approach, which can induce favorable interfacial interactions between electrocatalysts and significantly improve the electron transfer kinetics of electrodes, generated hybrid biofuel cells with high power output and good operational stability. (phys.org)
- The method induced favorable interfacial interactions between electrocatalysts and improved electron transfer kinetics of electrodes. (phys.org)
- In contrast, we were unable to identify electron density for hydrophobic fragments, confirming that hydrophobic interactions are important for inhibitor affinity but of minor importance for ligand recognition. (rcsb.org)
Surfactants2
- The study of the different hydrophobic/hydrophilic interactions in the Gemini surfactant-sacharide-water mixtures are very helpful to understand the structural behaviour of Gemini surfactants in the view of their biological significance. (degruyter.com)
- His study includes, inter alia, evaluating different (co)polymer systems on their solution behavior as well as the different hydrophilic-hydrophobic interactions and, investigating their potential use as carriers for active ingredients and as surfactants for emulsions. (ugent.be)
Aromatic1
- The modeling study showed that the lignin-phenanthrene interaction is mostly hydrophobic in nature being largely determined by the π-stacking interaction between the aromatic groups of the interacting partners. (nih.gov)
Biological1
- When researching biocompatible coatings for implant materials, one crucial parameter is the interaction of the implant with its biological environment. (anton-paar.com)
Functional1
- Water-mediated collagen and mineral nanoparticle interactions guide functional deformation of human tooth dentin. (mpg.de)
Properties4
- It is a hydrophobic phase with pronounced hydrophilic properties. (mn-net.com)
- Typical studies on biomaterials include measuring hardness and structural properties, characterization of surface charge, surface interaction, hydrophobic/hydrophilic properties, and many more. (anton-paar.com)
- Taking advantage of hydrophobic interactions and self-recognition properties of the BTA units, the 'free' BTAs are captured into the interior of the SCPN in water as evidenced by fluorescence studies. (stanford.edu)
- While the f-SiO2 NPs-modified PVDF nanofibres exclusively allow the transport of water vapour, the AgNPs/f-MWCNTs active provides hydrophilic and biocidal (i.e., biofouling control) properties. (ugent.be)
Active2
- Moreover, MSC supporting material selection is fundamental to allow for an active interaction with cells. (nature.com)
- The analysis of the docking results, which takes into account the hydrophilic and hydrophobic interactions betweenthe ligands and the target, identified N-(4-bromophenyl)-4,5-bis(4 hydroxyphenyl)thiophene-2-carboxamide (6k) having high binding free energy of −11.67 kcal/mole (comparable with standard diclofenac sodium) and the best docking score, indicating effective binding of the compound 6k at the active site. (ias.ac.in)
Transition1
- In particular, Raman-MCR is used to observe the presence and extent of water penetration into micelle interiors, and partial molar volume results from density measurements of deep-cavity cavitands demonstrate experimental observation of a hydrophobic cavity dewetting transition. (purdue.edu)
Concentration1
- The effects of temperature and concentration/strength of the solutions on the interaction behaviour were analysed by conductivity studies over a wide temperature (293.15-313.15) K and concentration range of the saccharides as well as of the surfactant. (degruyter.com)
Effect3
- The void created was immediately filled by Kauzmann's idea of hydrophobic ( HφO ) effect which reigned supreme in biochemical literature for over 50 years (1960-2010). (scirp.org)
- Cracks in the HB-inventory argument on one hand, and doubts about the adequacy of Kauzmann's model for the HφO effect, have led to a comeback of the HBs, along with a host of new hydrophilic ( HφI ) effects. (scirp.org)
- Brooks, D. E. Barrier Capacity Of Hydrophilic Polymer Brushes To Prevent Hydrophobic Interactions: Effect Of Graft Density And Hydrophilicity . (ubc.ca)
Study2
- In order to study the immune escape of Omicron in more detail, we comprehensively and systematically studied the interaction between the antibodies reported in PDB and current Omicron strains. (nature.com)
- In the present study, the interaction behaviour of 12-2-12 Gemini surfactant in aqueous saccharide solutions (lactose and maltodextrin solutions) is investigated using density, sound velocity and viscosity measurements. (degruyter.com)
Side1
- 2003). Both main-chain and side-chain atoms of compstatin are thought to be involved in interaction with C3 (Sahu et al. (justia.com)
Found1
- They found that when the size of the hydrophilic dendron becomes too large, it limits 1D growth, producing objects that are restricted in size and globular in shape. (europa.eu)
Result1
- Such interactions could not only result in injury to the patient but also inactivation of the nanorobots with a subsequent failure of the nanomedical mission. (nanomedicine.com)
Essential1
- indicating essential involvement of specific interactions. (lu.se)
Peptide3
- The peptide-surfactant interactions were studied by means of circular dichroism spectroscopy and binding isotherms, as well as by 1D and 2D NMR. (lu.se)
- The interaction yields an increased amount of alpha-helix conformation in the peptide. (lu.se)
- Researchers created a small library of charge-neutral dendritic peptide amphiphiles with a branched nonaphenylalanine-based core that was conjugated to hydrophilic dendrons of variable steric demand. (europa.eu)
Structure1
- In absence of local interactions, native structure formation does not occur for the temperatures considered. (lu.se)
Large1
- Like other members of the lipocalin family, BLG these specific interactions have been shown to be critical for has a -barrel fold with a large internal cavity that binds dimer stability (Kobayashi et al. (lu.se)
Chemical1
- This allows the filter to be used with no need to pre-wet with IPA and flush, which reduces chemical interaction and eliminates a potential source of contamination and reduces chemical usage. (3m.com)
Close1
- Newer strategies recognize the close biologic interactions between the skeletal cells and the immune cells. (medscape.com)
Method1
- This method exploits the ability of detergents to bind to hydrophobic resins. (sigmaaldrich.com)
Surface1
- Brooks, D. E. Surface Modification Of Polyvinyl Chloride Sheets Via Growth Of Hydrophilic Polymer Brushes . (ubc.ca)