title: Enzymatic digestibility of peptides cross-linked by ionizing radiation.
abstract: p6gestibility by proteolytic enzymes of peptides cross-linked by ionizing radiation was investigated. Small peptides of alanine and phenylalanine were chosen as model compounds and aminopeptidases and carboxypeptidases were used as proteolytic enzymes. Peptides exposed to gamma-radiation in aqueous solution were analysed by high-performance liquid chromatography before and after hydrolysis by aminopeptidase M, leucine aminopeptidase, carboxypeptidase A and carboxypeptidase Y. The results obtained clearly demonstrate the different actions of these enzymes on cross-linked aliphatic and aromatic peptides. Peptide bonds of cross-linked dipeptides of alanine were completely resistant to enzymatic hydrolysis whereas the enzymes, except for carboxypeptidase Y, cleaved all peptide bonds of cross-linked peptides of phenylalanine. The actions of the enzymes on these particular compounds are discussed in detail.
mesh_terms: D000626:Aminopeptidases; D018826:CD13 Antigens; D002268:Carboxypeptidases; D043422:Carboxypeptidases A; D002851:Chromatography, High Pressure Liquid; D003037:Cobalt Radioisotopes; D004151:Dipeptides / Q000528:radiation effects; D005720:Gamma Rays; D007931:Leucyl Aminopeptidase; D009842:Oligopeptides / Q000528:radiation effects; D010447:Peptide Hydrolases; D010455:Peptides / Q000528:radiation effects*
chemical_list: D003037:Cobalt Radioisotopes; D004151:Dipeptides; D009842:Oligopeptides; D010455:Peptides; C026650:phenylalanylphenylalanine; C041142:phenylalanyl-phenylalanyl-phenylalanine; C002956:alanylalanine; C026593:alanyl-alanyl-alanyl-alanine; D002268:Carboxypeptidases; D010447:Peptide Hydrolases; D000626:Aminopeptidases; D007931:Leucyl Aminopeptidase; D018826:CD13 Antigens; C022633:serine carboxypeptidase; D043422:Carboxypeptidases A