Amino Acid Chloromethyl Ketones: Inhibitors of SERINE ENDOPEPTIDASES and sulfhydryl group-containing enzymes. They act as alkylating agents and are known to interfere in the translation process.Tosyllysine Chloromethyl Ketone: An inhibitor of SERINE ENDOPEPTIDASES. Acts as an alkylating agent and is known to interfere with the translation process.Tosylphenylalanyl Chloromethyl Ketone: An inhibitor of Serine Endopeptidases. Acts as alkylating agent and is known to interfere with the translation process.KetonesBis(Chloromethyl) Ether: A substance that is an irritant to the eyes and respiratory tract and may be carcinogenic.Protease Inhibitors: Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).Serine Proteinase Inhibitors: Exogenous or endogenous compounds which inhibit SERINE ENDOPEPTIDASES.Ketone Bodies: The metabolic substances ACETONE; 3-HYDROXYBUTYRIC ACID; and acetoacetic acid (ACETOACETATES). They are produced in the liver and kidney during FATTY ACIDS oxidation and used as a source of energy by the heart, muscle and brain.Isoflurophate: A di-isopropyl-fluorophosphate which is an irreversible cholinesterase inhibitor used to investigate the NERVOUS SYSTEM.Amino Acids: 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.Anhydrides: Chemical compounds derived from acids by the elimination of a molecule of water.Peptide Hydrolases: Hydrolases that specifically cleave the peptide bonds found in PROTEINS and PEPTIDES. Examples of sub-subclasses for this group include EXOPEPTIDASES and ENDOPEPTIDASES.Trifluoroacetic Acid: A very strong halogenated derivative of acetic acid. It is used in acid catalyzed reactions, especially those where an ester is cleaved in peptide synthesis.Dansyl Compounds: Compounds that contain a 1-dimethylaminonaphthalene-5-sulfonyl group.Fluoroacetates: Derivatives of acetic acid with one or more fluorines attached. They are almost odorless, difficult to detect chemically, and very stable. The acid itself, as well as the derivatives that are broken down in the body to the acid, are highly toxic substances, behaving as convulsant poisons with a delayed action. (From Miall's Dictionary of Chemistry, 5th ed)Serine Endopeptidases: Any member of the group of ENDOPEPTIDASES containing at the active site a serine residue involved in catalysis.Kinetics: The rate dynamics in chemical or physical systems.Amino Acid Sequence: 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.Pyroglutamyl-Peptidase I: An enzyme that catalyzes the release of a N-terminal pyroglutamyl group from a polypeptide provided the next residue is not proline. It is inhibited by thiol-blocking reagents and occurs in mammalian tissues, microorganisms, and plants. (From Enzyme Nomenclature, 1992) EC 3.4.19.3.Pancreatic Elastase: 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.Sequence Homology, Amino Acid: The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.Endopeptidases: A subclass of PEPTIDE HYDROLASES that catalyze the internal cleavage of PEPTIDES or PROTEINS.p-Chloromercuribenzoic Acid: An organic mercurial used as a sulfhydryl reagent.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Molecular Weight: The sum of the weight of all the atoms in a molecule.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Chymotrypsin: 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.Tosyl CompoundsTrypsin Inhibitors: Serine proteinase inhibitors which inhibit trypsin. They may be endogenous or exogenous compounds.Cysteine Endopeptidases: 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.Electrophoresis, Polyacrylamide Gel: Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.Treponema: A genus of microorganisms of the order SPIROCHAETALES, many of which are pathogenic and parasitic for man and animals.Hydrogen-Ion Concentration: 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)Molecular Sequence Data: 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.Amino Acid Substitution: 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.Leupeptins: 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.Phenylmethylsulfonyl Fluoride: An enzyme inhibitor that inactivates IRC-50 arvin, subtilisin, and the fatty acid synthetase complex.Enzyme Precursors: Physiologically inactive substances that can be converted to active enzymes.Peptide Fragments: Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.Structure-Activity Relationship: 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.Thrombin: An enzyme formed from PROTHROMBIN that converts FIBRINOGEN to FIBRIN.Porphyromonas gingivalis: 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.Hydrolysis: The process of cleaving a chemical compound by the addition of a molecule of water.Cloning, Molecular: 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.Trypsin: 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.Affinity Labels: Analogs of those substrates or compounds which bind naturally at the active sites of proteins, enzymes, antibodies, steroids, or physiological receptors. These analogs form a stable covalent bond at the binding site, thereby acting as inhibitors of the proteins or steroids.Cell Line: Established cell cultures that have the potential to propagate indefinitely.Cysteine Proteinase Inhibitors: Exogenous and endogenous compounds which inhibit CYSTEINE ENDOPEPTIDASES.Cysteine: A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.Oligopeptides: Peptides composed of between two and twelve amino acids.Cycloheximide: Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.Bacteroides: A genus of gram-negative, anaerobic, rod-shaped bacteria. Its organisms are normal inhabitants of the oral, respiratory, intestinal, and urogenital cavities of humans, animals, and insects. Some species may be pathogenic.NF-kappa B: Ubiquitous, inducible, nuclear transcriptional activator that binds to enhancer elements in many different cell types and is activated by pathogenic stimuli. The NF-kappa B complex is a heterodimer composed of two DNA-binding subunits: NF-kappa B1 and relA.Protein PrecursorsAmino Acids, Essential: Amino acids that are not synthesized by the human body in amounts sufficient to carry out physiological functions. They are obtained from dietary foodstuffs.Cattle: 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.Methyl n-Butyl Ketone: An industrial solvent which causes nervous system degeneration. MBK is an acronym often used to refer to it.Amino Acid Transport Systems: Cellular proteins and protein complexes that transport amino acids across biological membranes.Acetoacetates: Salts and derivatives of acetoacetic acid.Sequence Alignment: 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.3-Hydroxybutyric Acid: BUTYRIC ACID substituted in the beta or 3 position. It is one of the ketone bodies produced in the liver.Enzyme Activation: 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.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Base Sequence: The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.Amino Acid Motifs: Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.Cells, Cultured: 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.Protein Conformation: 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).Escherichia coli: 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.Mutation: 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.