Biomaterial Database

Prediction of the secondary structures of stefins and cystatins, the low-molecular mass protein inhibitors of cysteine proteinases. 1987

A Sali, and V Turk

A procedure for classifying proteins of known sequence into structurally similar groups was developed on the basis of the Argos parametric approach. It is shown that stefins and cystatins constitute two structurally well resolved, but homologous groups of proteins. Furthermore, it is very probable that segments of secondary structures within each family are conserved, although significant differences between stefins and cystatins are indicated at the level of secondary structure. Next, secondary structures of all sequenced stefins and cystatins were predicted and used in the construction of secondary structures of the "typical stefin" and the "typical cystatin". Results were interpreted in the light of evolution and inhibition mechanism: Alignment of the "typical stefin" versus the "typical cystatin" secondary structure segments suggests that the divergence of stefin and cystatin families did not occur by a gene fusion event, but only by a mechanism of substitution, insertion and/or deletion. The central region of low-molecular mass cystatins, which is assumed to interact with cysteine proteinases, is predicted to be in a beta-sheet conformation. This resembles the beta-sheet in the active site of "standard mechanism" serine proteinases inhibitors.

UI	MeSH Term	Description	Entries
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D011480	Protease Inhibitors	Compounds which inhibit or antagonize biosynthesis or actions of proteases (ENDOPEPTIDASES).	Antiprotease,Endopeptidase Inhibitor,Endopeptidase Inhibitors,Peptidase Inhibitor,Peptidase Inhibitors,Peptide Hydrolase Inhibitor,Peptide Hydrolase Inhibitors,Peptide Peptidohydrolase Inhibitor,Peptide Peptidohydrolase Inhibitors,Protease Antagonist,Protease Antagonists,Antiproteases,Protease Inhibitor,Antagonist, Protease,Antagonists, Protease,Hydrolase Inhibitor, Peptide,Hydrolase Inhibitors, Peptide,Inhibitor, Endopeptidase,Inhibitor, Peptidase,Inhibitor, Peptide Hydrolase,Inhibitor, Peptide Peptidohydrolase,Inhibitor, Protease,Inhibitors, Endopeptidase,Inhibitors, Peptidase,Inhibitors, Peptide Hydrolase,Inhibitors, Peptide Peptidohydrolase,Inhibitors, Protease,Peptidohydrolase Inhibitor, Peptide,Peptidohydrolase Inhibitors, Peptide
D011487	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).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011506	Proteins	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.	Gene Products, Protein,Gene Proteins,Protein,Protein Gene Products,Proteins, Gene
D002627	Chemistry, Physical	The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.	Physical Chemistry,Chemistries, Physical,Physical Chemistries
D000595	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.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D015853	Cysteine Proteinase Inhibitors	Exogenous and endogenous compounds which inhibit CYSTEINE ENDOPEPTIDASES.	Acid Cysteine Proteinase Inhibitor,Cysteine Protease Inhibitor,Cysteine Protease Inhibitors,Cysteine Proteinase Antagonist,Cysteine Proteinase Antagonists,Cysteine Proteinase Inhibitor,Cysteine Proteinase Inhibitors, Endogenous,Cysteine Proteinase Inhibitors, Exogenous,alpha-Cysteine Protease Inhibitor,Acid Cysteine Proteinase Inhibitors,alpha-Cysteine Protease Inhibitors,Antagonist, Cysteine Proteinase,Antagonists, Cysteine Proteinase,Inhibitor, Cysteine Protease,Inhibitor, Cysteine Proteinase,Inhibitor, alpha-Cysteine Protease,Inhibitors, Cysteine Protease,Inhibitors, Cysteine Proteinase,Inhibitors, alpha-Cysteine Protease,Protease Inhibitor, Cysteine,Protease Inhibitor, alpha-Cysteine,Protease Inhibitors, Cysteine,Protease Inhibitors, alpha-Cysteine,Proteinase Antagonist, Cysteine,Proteinase Antagonists, Cysteine,Proteinase Inhibitor, Cysteine,Proteinase Inhibitors, Cysteine,alpha Cysteine Protease Inhibitor,alpha Cysteine Protease Inhibitors
D015891	Cystatins	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.	Cystatin,Cystatin Superfamily,Stefin,Cystatin-Related Proteins,Stefins,Type 1 Cystatins,Type 2 Cystatins,Type 3 Cystatins,Type I Cystatins,Type II Cystatins,Type III Cystatins,Cystatin Related Proteins,Cystatins, Type 1,Cystatins, Type 2,Cystatins, Type 3,Cystatins, Type I,Cystatins, Type II,Cystatins, Type III
D055313	Cystatin B	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.	Liver Thiol Proteinase Inhibitor,Stefin B
D055598	Chemical Phenomena	The composition, structure, conformation, and properties of atoms and molecules, and their reaction and interaction processes.	Chemical Concepts,Chemical Processes,Physical Chemistry Concepts,Physical Chemistry Processes,Physicochemical Concepts,Physicochemical Phenomena,Physicochemical Processes,Chemical Phenomenon,Chemical Process,Physical Chemistry Phenomena,Physical Chemistry Process,Physicochemical Phenomenon,Physicochemical Process,Chemical Concept,Chemistry Process, Physical,Chemistry Processes, Physical,Concept, Chemical,Concept, Physical Chemistry,Concept, Physicochemical,Concepts, Chemical,Concepts, Physical Chemistry,Concepts, Physicochemical,Phenomena, Chemical,Phenomena, Physical Chemistry,Phenomena, Physicochemical,Phenomenon, Chemical,Phenomenon, Physicochemical,Physical Chemistry Concept,Physicochemical Concept,Process, Chemical,Process, Physical Chemistry,Process, Physicochemical,Processes, Chemical,Processes, Physical Chemistry,Processes, Physicochemical