(redirected from Endoproteinase)
Also found in: Dictionary, Medical.


An enzyme that acts upon the centrally located peptide bonds of a protein molecule.



an enzyme of the class of hydrolases. Endo-peptidases catalyze the decomposition of internal peptide bonds in proteins and peptides. The speed of hydrolysis of a given peptide bond by different endopeptidases depends on the substrate specificity of the enzyme and the spatial accessibility of the given peptide bond, especially if the substrate is a native, not denatured, protein. It does not depend on the size of the molecules of the substrate, that is, the length of the polypeptide chain. The substrate specificity of an endopeptidase consists in the ability of a given enzyme to hydrolyze the peptide bonds between certain amino acid residues with the greatest speed. For example, chy-motrypsin very rapidly hydrolyzes peptide bonds together with aromatic amino acids; trypsin does the same with diamino acids. Endopeptidases are classified as extracellular or intracellular (tissular). Extracellular endopeptidases are secreted into the digestive cavity of animals (for example, enterokinase) or simply into the external environment (the exo-enzymes of bacteria).

The use of endopeptidases in determining the primary structure of proteins is based on their properties.

References in periodicals archive ?
Enzymatic digests of native lectin protein with endoproteinase C were separated by RP-HPLC and subjected to protein sequencing, resulting in the partial N-terminal and an internal fragment of amino acid sequence of lectin, identified to be sequence PLQGRSQKTE and GNEDCLDLRT, respectively.
2] terminus of cTnT is rich in glutamic acid residues, which produces very small peptides when digested with endoproteinase Glu-C, and low in lysine and arginine residues, which produces very large peptides when digested with trypsin or endoproteinase Lys-C.
To confirm these assumptions, we digested the globin chains in the fractions with endoproteinase Glu-C or trypsin.
Peptide mapping and evaluation of glycopeptide microheterogeneity derived from endoproteinase digestion of erythropoietin by affinity high-performance capillary electrophoresis.
In accordance with the IFCC protocol, peptide linkages C-terminal to the glutamic acid residues in Hb components in the hemolysates were cleaved with endoproteinase Glu-C (Sigma-Aldrich) (1).
Next, the hemolysate is incubated with the endoproteinase Glu-C for 18 hours at 37[degrees]C to cleave Hb into peptides, whereby the specific glycated and non-glycated N-terminal peptides of the [beta]-chain of Hb are measured by either capillary electrophoresis or electrospray ionization mass spectrometry.
4]-labeled sample was then subjected to proteolytic digestion with endoproteinase Asp-N, which cleaves at aspartic acid residues, or aminopeptidase I, which nonspecifically removes amino acid residues inwards from N-terminus, for I hour at room temperature and followed by immunoprecipitation.
In the first step, Hb from washed and lysed erythrocytes is cleaved into peptides by the proteolytic enzyme endoproteinase Glu-C.
The gels were silver stained, and the PSA band was digested with endo Lys C, an endoproteinase from Lysobacter enzymogenes, as described by Shevchenko et al.