A subclass of peptide hydrolases that depend on a CYSTEINE residue for their activity.

A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.

ENDOPEPTIDASES which have a cysteine involved in the catalytic process. This group of enzymes is inactivated by CYSTEINE PROTEINASE INHIBITORS such as CYSTATINS and SULFHYDRYL REAGENTS.

Exogenous and endogenous compounds which inhibit CYSTEINE ENDOPEPTIDASES.

Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).

A group of lysosomal proteinases or endopeptidases found in aqueous extracts of a variety of animal tissues. They function optimally within an acidic pH range. The cathepsins occur as a variety of enzyme subtypes including SERINE PROTEASES; ASPARTIC PROTEINASES; and CYSTEINE PROTEASES.

A ubiquitously-expressed cysteine protease that plays an enzymatic role in POST-TRANSLATIONAL PROTEIN PROCESSING of proteins within SECRETORY GRANULES.

A homologous group of endogenous CYSTEINE PROTEINASE INHIBITORS. The cystatins inhibit most CYSTEINE ENDOPEPTIDASES such as PAPAIN, and other peptidases which have a sulfhydryl group at the active site.

A lysosomal cysteine proteinase with a specificity similar to that of PAPAIN. The enzyme is present in a variety of tissues and is important in many physiological and pathological processes. In pathology, cathepsin B has been found to be involved in DEMYELINATION; EMPHYSEMA; RHEUMATOID ARTHRITIS, and NEOPLASM INVASIVENESS.

The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.

A proteolytic enzyme obtained from Carica papaya. It is also the name used for a purified mixture of papain and CHYMOPAPAIN that is used as a topical enzymatic debriding agent. EC 3.4.22.2.

Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.

A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.

Enzyme of the human immunodeficiency virus that is required for post-translational cleavage of gag and gag-pol precursor polyproteins into functional products needed for viral assembly. HIV protease is an aspartic protease encoded by the amino terminus of the pol gene.

Cysteine proteinase found in many tissues. Hydrolyzes a variety of endogenous proteins including NEUROPEPTIDES; CYTOSKELETAL PROTEINS; proteins from SMOOTH MUSCLE; CARDIAC MUSCLE; liver; platelets; and erythrocytes. Two subclasses having high and low calcium sensitivity are known. Removes Z-discs and M-lines from myofibrils. Activates phosphorylase kinase and cyclic nucleotide-independent protein kinase. This enzyme was formerly listed as EC 3.4.22.4.

Hydrolases that specifically cleave the peptide bonds found in PROTEINS and PEPTIDES. Examples of sub-subclasses for this group include EXOPEPTIDASES and ENDOPEPTIDASES.

Any member of the group of ENDOPEPTIDASES containing at the active site a serine residue involved in catalysis.

A cysteine protease that is highly expressed in OSTEOCLASTS and plays an essential role in BONE RESORPTION as a potent EXTRACELLULAR MATRIX-degrading enzyme.

A lysosomal papain-related cysteine proteinase that is expressed in a broad variety of cell types.

A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.

The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.

Proteins prepared by recombinant DNA technology.

Peptides composed of two amino acid units.

A long pro-domain caspase that has specificity for the precursor form of INTERLEUKIN-1BETA. It plays a role in INFLAMMATION by catalytically converting the inactive forms of CYTOKINES such as interleukin-1beta to their active, secreted form. Caspase 1 is referred as interleukin-1beta converting enzyme and is frequently abbreviated ICE.

A prokaryotic ATP-dependent protease that plays a role in the degradation of many abnormal proteins. It is a tetramer of 87-kDa subunits, each of which contains a proteolytic site and a ATP-binding site.

An enzyme that catalyzes the conversion of L-CYSTEINE to 3-sulfinoalanine (3-sulfino-L-alanine) in the CYSTEINE metabolism and TAURINE and hypotaurine metabolic pathways.

A genus of tapeworms of the family Diphyllobothriidae, which are parasites of fish-eating cats, dogs, and birds. Infection in man is caused by eating undercooked fish. The larval form is called SPARGANUM.

Exogenous or endogenous compounds which inhibit SERINE ENDOPEPTIDASES.

A family of intracellular CYSTEINE ENDOPEPTIDASES that play a role in regulating INFLAMMATION and APOPTOSIS. They specifically cleave peptides at a CYSTEINE amino acid that follows an ASPARTIC ACID residue. Caspases are activated by proteolytic cleavage of a precursor form to yield large and small subunits that form the enzyme. Since the cleavage site within precursors matches the specificity of caspases, sequential activation of precursors by activated caspases can occur.

Physiologically inactive substances that can be converted to active enzymes.

The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.

The parts of a macromolecule that directly participate in its specific combination with another molecule.

Proteases that contain proteolytic core domains and ATPase-containing regulatory domains. They are usually comprised of large multi-subunit assemblies. The domains can occur within a single peptide chain or on distinct subunits.

Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.

An enzyme that catalyzes the biosynthesis of cysteine in microorganisms and plants from O-acetyl-L-serine and hydrogen sulfide. This enzyme was formerly listed as EC 4.2.99.8.

The rate dynamics in chemical or physical systems.

The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.

The process of cleaving a chemical compound by the addition of a molecule of water.

A genus of lung flukes of the family Troglotrematidae infecting humans and animals. This genus consists of several species one of which is PARAGONIMUS WESTERMANI, a common lung fluke in humans.

The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.

Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.

The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.

A papain-like cysteine protease that has specificity for amino terminal dipeptides. The enzyme plays a role in the activation of several pro-inflammatory serine proteases by removal of their aminoterminal inhibitory dipeptides. Genetic mutations that cause loss of cathepsin C activity in humans are associated with PAPILLON-LEFEVRE DISEASE.

Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.

Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.

Proteins found in any species of helminth.

An essential branched-chain amino acid important for hemoglobin formation.

A species of gram-positive, coccoid bacteria isolated from skin lesions, blood, inflammatory exudates, and the upper respiratory tract of humans. It is a group A hemolytic Streptococcus that can cause SCARLET FEVER and RHEUMATIC FEVER.

A class of morphologically heterogeneous cytoplasmic particles in animal and plant tissues characterized by their content of hydrolytic enzymes and the structure-linked latency of these enzymes. The intracellular functions of lysosomes depend on their lytic potential. The single unit membrane of the lysosome acts as a barrier between the enzymes enclosed in the lysosome and the external substrate. The activity of the enzymes contained in lysosomes is limited or nil unless the vesicle in which they are enclosed is ruptured. Such rupture is supposed to be under metabolic (hormonal) control. (From Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)

Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.

Any of various enzymatically catalyzed post-translational modifications of PEPTIDES or PROTEINS in the cell of origin. These modifications include carboxylation; HYDROXYLATION; ACETYLATION; PHOSPHORYLATION; METHYLATION; GLYCOSYLATION; ubiquitination; oxidation; proteolysis; and crosslinking and result in changes in molecular weight and electrophoretic motility.

Protein-digesting and milk-clotting enzymes found in PINEAPPLE fruit juice and stem tissue. Enzymes from the two sources are distinguished as fruit bromelain and stem bromelain. This enzyme was formerly listed as EC 3.4.22.4.

Conversion of an inactive form of an enzyme to one possessing metabolic activity. It includes 1, activation by ions (activators); 2, activation by cofactors (coenzymes); and 3, conversion of an enzyme precursor (proenzyme or zymogen) to an active enzyme.

Proteins found in any species of bacterium.

An intracellular cystatin subtype that is found in a broad variety of cell types. It is a cytosolic enzyme inhibitor that protects the cell against the proteolytic action of lysosomal enzymes such as CATHEPSINS.

The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)

A cytastin subtype found at high levels in the SKIN and in BLOOD CELLS. Cystatin A incorporates into the cornified cell envelope of stratified squamous epithelial cells and may play a role in bacteriostatic properties of skin.

Established cell cultures that have the potential to propagate indefinitely.

The region of an enzyme that interacts with its substrate to cause the enzymatic reaction.

Cleavage of proteins into smaller peptides or amino acids either by PROTEASES or non-enzymatically (e.g., Hydrolysis). It does not include Protein Processing, Post-Translational.

Extracellular protease inhibitors that are secreted from FIBROBLASTS. They form a covalent complex with SERINE PROTEASES and can mediate their cellular internalization and degradation.

Peptides composed of between two and twelve amino acids.

One of the mechanisms by which CELL DEATH occurs (compare with NECROSIS and AUTOPHAGOCYTOSIS). Apoptosis is the mechanism responsible for the physiological deletion of cells and appears to be intrinsically programmed. It is characterized by distinctive morphologic changes in the nucleus and cytoplasm, chromatin cleavage at regularly spaced sites, and the endonucleolytic cleavage of genomic DNA; (DNA FRAGMENTATION); at internucleosomal sites. This mode of cell death serves as a balance to mitosis in regulating the size of animal tissues and in mediating pathologic processes associated with tumor growth.

A cysteine endopeptidase found in NATURAL KILLER CELLS and CYTOTOXIC T-LYMPHOCYTES. It may have a specific function in the mechanism or regulation of cytolytic activity of immune cells.

Proteins found in any species of protozoan.

A group of acylated oligopeptides produced by Actinomycetes that function as protease inhibitors. They have been known to inhibit to varying degrees trypsin, plasmin, KALLIKREINS, papain and the cathepsins.

Compounds containing the -SH radical.

The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.

A short pro-domain caspase that plays an effector role in APOPTOSIS. It is activated by INITIATOR CASPASES such as CASPASE 9. Isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.

A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.

An extracellular cystatin subtype that is abundantly expressed in bodily fluids. It may play a role in the inhibition of interstitial CYSTEINE PROTEASES.

Members of the peptidase C19 family which regulate signal transduction by removing UBIQUITIN from specific protein substrates via a process known as deubiquitination or deubiquitylation.

Inhibitors of SERINE ENDOPEPTIDASES and sulfhydryl group-containing enzymes. They act as alkylating agents and are known to interfere in the translation process.

A family of serine proteinase inhibitors which are similar in amino acid sequence and mechanism of inhibition, but differ in their specificity toward proteolytic enzymes. This family includes alpha 1-antitrypsin, angiotensinogen, ovalbumin, antiplasmin, alpha 1-antichymotrypsin, thyroxine-binding protein, complement 1 inactivators, antithrombin III, heparin cofactor II, plasminogen inactivators, gene Y protein, placental plasminogen activator inhibitor, and barley Z protein. Some members of the serpin family may be substrates rather than inhibitors of SERINE ENDOPEPTIDASES, and some serpins occur in plants where their function is not known.

A short pro-domain caspase that plays an effector role in APOPTOSIS. It is activated by INITIATOR CASPASES such as CASPASE 7; CASPASE 8; and CASPASE 10. Isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.

Synthetic or naturally occurring substances related to coumarin, the delta-lactone of coumarinic acid.

The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)

The sum of the weight of all the atoms in a molecule.

The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.

A ubiquitously-expressed cysteine peptidase that exhibits carboxypeptidase activity. It is highly expressed in a variety of immune cell types and may play a role in inflammatory processes and immune responses.

N-acylated oligopeptides isolated from culture filtrates of Actinomycetes, which act specifically to inhibit acid proteases such as pepsin and renin.

Vinyl compounds, in the context of medical materials, refer to synthetic polymers made from vinyl chloride or vinyl acetate monomers, which are used in the production of various medical devices and supplies such as blood bags, intravenous (IV) bags, tubing, and gloves due to their flexibility, transparency, and resistance to chemicals and heat.

A covalently linked dimeric nonessential amino acid formed by the oxidation of CYSTEINE. Two molecules of cysteine are joined together by a disulfide bridge to form cystine.

A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 3.4.21.4.

Single-stranded complementary DNA synthesized from an RNA template by the action of RNA-dependent DNA polymerase. cDNA (i.e., complementary DNA, not circular DNA, not C-DNA) is used in a variety of molecular cloning experiments as well as serving as a specific hybridization probe.

Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.

The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.

A cystatin subtype that has a diverse tissue distribution, target specificity, and functions as an endogenous inhibitor of lysosomal cysteine proteases.

Infection with TREMATODA of the genus PARAGONIMUS.

Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.

Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.

A genus of parasitic nematode worms which infest the duodenum and stomach of domestic and wild herbivores, which ingest it with the grasses (POACEAE) they eat. Infestation of man is accidental.

A parasitic hemoflagellate of the subgenus Leishmania leishmania that infects man and animals including rodents. The Leishmania mexicana complex causes both cutaneous (LEISHMANIASIS, CUTANEOUS) and diffuse cutaneous leishmaniasis (LEISHMANIASIS, DIFFUSE CUTANEOUS) and includes the subspecies amazonensis, garnhami, mexicana, pifanoi, and venezuelensis. L. m. mexicana causes chiclero ulcer, a form of cutaneous leishmaniasis (LEISHMANIASIS, CUTANEOUS) in the New World. The sandfly, Lutzomyia, appears to be the vector.

The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).

Sulfones are a class of organic compounds containing the functional group with a sulfur atom bonded to two oxygen atoms and another organic group, widely used in pharmaceuticals, particularly for the treatment of bacterial infections, leprosy, and certain types of cancer.

The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.

The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.

A long pro-domain caspase that contains a caspase recruitment domain in its pro-domain region. Activation of this enzyme can occur via the interaction of its caspase recruitment domain with CARD SIGNALING ADAPTOR PROTEINS. Caspase 2 plays a role in APOPTOSIS by cleaving and activating effector pro-caspases. Several isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.

A sulfhydryl proteinase with cysteine at the active site from ficus latex. Preferential cleavage is at tyrosine and phenylalanine residues. EC 3.4.22.3.

The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.

ENDOPEPTIDASES which use a metal such as ZINC in the catalytic mechanism.

Infection with nematodes of the genus HAEMONCHUS, characterized by digestive abnormalities and anemia similar to that from hookworm infestation.

Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.

An alkylating sulfhydryl reagent. Its actions are similar to those of iodoacetate.

Endogenous and exogenous compounds and that either inhibit CASPASES or prevent their activation.

The agent of South American trypanosomiasis or CHAGAS DISEASE. Its vertebrate hosts are man and various domestic and wild animals. Insects of several species are vectors.

A species of parasitic protozoa causing ENTAMOEBIASIS and amebic dysentery (DYSENTERY, AMEBIC). Characteristics include a single nucleus containing a small central karyosome and peripheral chromatin that is finely and regularly beaded.

Proteins synthesized by organisms belonging to the phylum ARTHROPODA. Included in this heading are proteins from the subdivisions ARACHNIDA; CRUSTACEA; and HORSESHOE CRABS. Note that a separate heading for INSECT PROTEINS is listed under this heading.

A sub-subclass of endopeptidases that depend on an ASPARTIC ACID residue for their activity.

Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in enzyme synthesis.

Protein precursors, also known as proproteins or prohormones, are inactive forms of proteins that undergo post-translational modification, such as cleavage, to produce the active functional protein or peptide hormone.

A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).

Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.

Identification of proteins or peptides that have been electrophoretically separated by blot transferring from the electrophoresis gel to strips of nitrocellulose paper, followed by labeling with antibody probes.

Short sequences (generally about 10 base pairs) of DNA that are complementary to sequences of messenger RNA and allow reverse transcriptases to start copying the adjacent sequences of mRNA. Primers are used extensively in genetic and molecular biology techniques.

Antigens from the house dust mites (DERMATOPHAGOIDES), mainly D. farinae and D. pteronyssinus. They are proteins, found in mite feces or mite extracts, that can cause ASTHMA and other allergic diseases such as perennial rhinitis (RHINITIS, ALLERGIC, PERENNIAL) and atopic dermatitis (DERMATITIS, ATOPIC). More than 11 groups of Dermatophagoides ALLERGENS have been defined. Group I allergens, such as Der f I and Der p I from the above two species, are among the strongest mite immunogens in humans.

A reagent commonly used in biochemical studies as a protective agent to prevent the oxidation of SH (thiol) groups and for reducing disulphides to dithiols.

A sequence of amino acids in a polypeptide or of nucleotides in DNA or RNA that is similar across multiple species. A known set of conserved sequences is represented by a CONSENSUS SEQUENCE. AMINO ACID MOTIFS are often composed of conserved sequences.

Diazomethane is an extremely hazardous and unstable organic compound, (CH2)N=N=O, with a methane substituted diazo group, that is highly explosive when heated, shocked or contaminated, and used as a powerful methylating agent in chemical syntheses, but its production and handling require special expertise and equipment due to the high risks involved.

A derivative of ACETIC ACID that contains one IODINE atom attached to its methyl group.

A protease of broad specificity, obtained from dried pancreas. Molecular weight is approximately 25,000. The enzyme breaks down elastin, the specific protein of elastic fibers, and digests other proteins such as fibrin, hemoglobin, and albumin. EC 3.4.21.36.

A species of protozoa that is the causal agent of falciparum malaria (MALARIA, FALCIPARUM). It is most prevalent in the tropics and subtropics.

A species of gram-negative, anaerobic, rod-shaped bacteria originally classified within the BACTEROIDES genus. This bacterium produces a cell-bound, oxygen-sensitive collagenase and is isolated from the human mouth.

Infection of animals, including fish and man, with a developmental stage of Diphyllobothrium. This stage has recently been referred to as a plerocercoid but the name sparganum has persisted. Therefore, infection of fish or other animals with the plerocercoid larvae is sparganosis. Fish-eating mammals, including man, are the final hosts.

A long pro-domain caspase that contains a death effector domain in its pro-domain region. Activation of this enzyme can occur via the interaction of its N-terminal death effector domain with DEATH DOMAIN RECEPTOR SIGNALING ADAPTOR PROTEINS. Caspase 10 plays a role in APOPTOSIS by cleaving and activating EFFECTOR CASPASES. Several isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.

Toxins produced, especially by bacterial or fungal cells, and released into the culture medium or environment.

An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.

Immunologic method used for detecting or quantifying immunoreactive substances. The substance is identified by first immobilizing it by blotting onto a membrane and then tagging it with labeled antibodies.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

A serine endopeptidase secreted by the pancreas as its zymogen, CHYMOTRYPSINOGEN and carried in the pancreatic juice to the duodenum where it is activated by TRYPSIN. It selectively cleaves aromatic amino acids on the carboxyl side.

The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES.

Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.

Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.

Proteins found in any species of virus.

Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion.

Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.

Invertebrate organisms that live on or in another organism (the host), and benefit at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.

A group of closely-related cystatins found in SALIVA.

An ubiquitously-expressed lysosomal cysteine protease that is involved in protein processing. The enzyme has both endopeptidase and aminopeptidase activities.

Elements of limited time intervals, contributing to particular results or situations.

A family of SERINE ENDOPEPTIDASES isolated from Bacillus subtilis. EC 3.4.21.-

Transport proteins that carry specific substances in the blood or across cell membranes.

Recombinant proteins produced by the GENETIC TRANSLATION of fused genes formed by the combination of NUCLEIC ACID REGULATORY SEQUENCES of one or more genes with the protein coding sequences of one or more genes.

Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.

Separation technique in which the stationary phase consists of ion exchange resins. The resins contain loosely held small ions that easily exchange places with other small ions of like charge present in solutions washed over the resins.

The degree of pathogenicity within a group or species of microorganisms or viruses as indicated by case fatality rates and/or the ability of the organism to invade the tissues of the host. The pathogenic capacity of an organism is determined by its VIRULENCE FACTORS.

A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.

An ATP-dependent protease found in prokaryotes, CHLOROPLASTS, and MITOCHONDRIA. It is a soluble multisubunit complex that plays a role in the degradation of many abnormal proteins.

Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.

A short pro-domain caspase that plays an effector role in APOPTOSIS. It is activated by INITIATOR CASPASES such as CASPASE 3 and CASPASE 10. Several isoforms of this protein exist due to multiple alternative splicing of its MESSENGER RNA.

Proteases which use a metal, normally ZINC, in the catalytic mechanism. This group of enzymes is inactivated by metal CHELATORS.

Chemical agents that react with SH groups. This is a chemically diverse group that is used for a variety of purposes. Among these are enzyme inhibition, enzyme reactivation or protection, and labelling.

A mixture of related phosphoproteins occurring in milk and cheese. The group is characterized as one of the most nutritive milk proteins, containing all of the common amino acids and rich in the essential ones.

The relationship between an invertebrate and another organism (the host), one of which lives at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically.

"Semicarbazones are compounds formed when semicarbazide reacts with an aldehyde or ketone, creating a bond that includes a hydrogen bond donor and acceptor, which can be useful in the identification and analysis of carbonyl groups in organic chemistry and medicinal research."

The lipid- and protein-containing, selectively permeable membrane that surrounds the cytoplasm in prokaryotic and eukaryotic cells.

Organic compounds that include a cyclic ether with three ring atoms in their structure. They are commonly used as precursors for POLYMERS such as EPOXY RESINS.

The relationships of groups of organisms as reflected by their genetic makeup.

Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.

A cysteine endopeptidase isolated from papaya latex. Preferential cleavage at glutamic and aspartic acid residues. EC 3.4.22.6.

The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.

The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.

Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.

Splitting the DNA into shorter pieces by endonucleolytic DNA CLEAVAGE at multiple sites. It includes the internucleosomal DNA fragmentation, which along with chromatin condensation, are considered to be the hallmarks of APOPTOSIS.

A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.

A group of atoms or molecules attached to other molecules or cellular structures and used in studying the properties of these molecules and structures. Radioactive DNA or RNA sequences are used in MOLECULAR GENETICS to detect the presence of a complementary sequence by NUCLEIC ACID HYBRIDIZATION.

A species of Trypanosome hemoflagellates that is carried by tsetse flies and causes severe anemia in cattle. These parasites are also found in horses, sheep, goats, and camels.

A plant genus of the family BROMELIACEAE known for the edible fruit that is the source of BROMELAINS.

Proteins encoded by a VIRAL GENOME that are produced in the organisms they infect, but not packaged into the VIRUS PARTICLES. Some of these proteins may play roles within the infected cell during VIRUS REPLICATION or act in regulation of virus replication or VIRUS ASSEMBLY.

The relationship between the dose of an administered drug and the response of the organism to the drug.

The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.

The process by which two molecules of the same chemical composition form a condensation product or polymer.

Endogenous peptides present in most body fluids. Certain enzymes convert them to active KININS which are involved in inflammation, blood clotting, complement reactions, etc. Kininogens belong to the cystatin superfamily. They are cysteine proteinase inhibitors. HIGH-MOLECULAR-WEIGHT KININOGEN; (HMWK); is split by plasma kallikrein to produce BRADYKININ. LOW-MOLECULAR-WEIGHT KININOGEN; (LMWK); is split by tissue kallikrein to produce KALLIDIN.

The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.

The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.

An intracellular proteinase found in a variety of tissue. It has specificity similar to but narrower than that of pepsin A. The enzyme is involved in catabolism of cartilage and connective tissue. EC 3.4.23.5. (Formerly EC 3.4.4.23).

The first continuously cultured human malignant CELL LINE, derived from the cervical carcinoma of Henrietta Lacks. These cells are used for VIRUS CULTIVATION and antitumor drug screening assays.

Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.

Agents that cause agglutination of red blood cells. They include antibodies, blood group antigens, lectins, autoimmune factors, bacterial, viral, or parasitic blood agglutinins, etc.

The phenotypic manifestation of a gene or genes by the processes of GENETIC TRANSCRIPTION and GENETIC TRANSLATION.

Cell-surface components or appendages of bacteria that facilitate adhesion (BACTERIAL ADHESION) to other cells or to inanimate surfaces. Most fimbriae (FIMBRIAE, BACTERIAL) of gram-negative bacteria function as adhesins, but in many cases it is a minor subunit protein at the tip of the fimbriae that is the actual adhesin. In gram-positive bacteria, a protein or polysaccharide surface layer serves as the specific adhesin. What is sometimes called polymeric adhesin (BIOFILMS) is distinct from protein adhesin.

Enzymes that catalyze the cleavage of a carbon-nitrogen bond by means other than hydrolysis or oxidation. Subclasses are the AMMONIA-LYASES, the AMIDINE-LYASES, the amine-lyases, and other carbon-nitrogen lyases. EC 4.3.

The continuous sequence of changes undergone by living organisms during the post-embryonic developmental process, such as metamorphosis in insects and amphibians. This includes the developmental stages of apicomplexans such as the malarial parasite, PLASMODIUM FALCIPARUM.

Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.

A monocot family within the order Liliales. This family is divided by some botanists into other families such as Convallariaceae, Hyacinthaceae and Amaryllidaceae. Amaryllidaceae, which have inferior ovaries, includes CRINUM; GALANTHUS; LYCORIS; and NARCISSUS and are known for AMARYLLIDACEAE ALKALOIDS.

Inbred C57BL mice are a strain of laboratory mice that have been produced by many generations of brother-sister matings, resulting in a high degree of genetic uniformity and homozygosity, making them widely used for biomedical research, including studies on genetics, immunology, cancer, and neuroscience.

A genus of flagellate protozoans found in the blood and lymph of vertebrates and invertebrates, both hosts being required to complete the life cycle.

Serine proteinase inhibitors which inhibit trypsin. They may be endogenous or exogenous compounds.

A genus of trematode liver flukes of the family Opisthorchidae. It consists of the following species: O. felineus, O. noverca (Amphimerus noverca), and O. viverrini. The intermediate hosts are snails, fish, and AMPHIBIANS.

A sulfhydryl reagent that is widely used in experimental biochemical studies.

A short pro-domain caspase that is almost exclusively expressed in the EPIDERMIS and may play a role in the differentiation of epidermal KERATINOCYTES.

A long pro-domain caspase that contains a death effector domain in its pro-domain region. Caspase 8 plays a role in APOPTOSIS by cleaving and activating EFFECTOR CASPASES. Activation of this enzyme can occur via the interaction of its N-terminal death effector domain with DEATH DOMAIN RECEPTOR SIGNALING ADAPTOR PROTEINS.

Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.

Yeast-like ascomycetous fungi of the family Saccharomycetaceae, order SACCHAROMYCETALES isolated from exuded tree sap.

An essential amino acid that is required for the production of HISTAMINE.

The molecular designing of drugs for specific purposes (such as DNA-binding, enzyme inhibition, anti-cancer efficacy, etc.) based on knowledge of molecular properties such as activity of functional groups, molecular geometry, and electronic structure, and also on information cataloged on analogous molecules. Drug design is generally computer-assisted molecular modeling and does not include pharmacokinetics, dosage analysis, or drug administration analysis.

A species of lung fluke infecting humans and other animals, and found chiefly in Asia and the Far East.

Enzymes that catalyze the cleavage of a carbon-sulfur bond by means other than hydrolysis or oxidation. EC 4.4.

'Ketones' are organic compounds with a specific structure, characterized by a carbonyl group (a carbon double-bonded to an oxygen atom) and two carbon atoms, formed as byproducts when the body breaks down fats for energy due to lack of glucose, often seen in diabetes and starvation states.

A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.

A sub-class of PEPTIDE HYDROLASES that act only near the ends of polypeptide chains.

A genus of the family ARTERIVIRIDAE, in the order NIDOVIRALES. The type species is ARTERITIS VIRUS, EQUINE.