title: Trypsin activity reduced by an autocatalytically produced nonapeptide.
abstract: Trypsin, a serine protease enzyme plays a pivotal role in digestion and is autocatalytic. The crystal structure of a complex formed between porcine trypsin and an auto catalytically produced peptide is reported here. This complex shows a reduction in enzyme activity as compared to native beta-trypsin. The nonapeptide has a lysine, which is recognized by Asp 189 at the specificity pocket. The auto catalytically produced native nonapeptide is bound at the active site cleft like other trypsin inhibitors but the important interactions with the oxyanion hole are absent. The peptide covers only a part of the active site cleft and hence the enzyme activity is reduced rather than being inhibited.
authors.affiliation: Department of Crystallography and Biophysics, University of Madras, Guindy Campus, Guindy, Chennai-600025, India.
authors.forename: B S
authors.initials: BS
authors.lastname: Ibrahim
authors.forename: N
authors.initials: N
authors.lastname: Shamaladevi
authors.forename: V
authors.initials: V
authors.lastname: Pattabhi
mesh_terms: D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D013552:Swine; D014357:Trypsin / Q000737:chemistry / Q000378:metabolism*; D014361:Trypsin Inhibitors / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry
chemical_list: D010455:Peptides; D014361:Trypsin Inhibitors; D014867:Water; D014357:Trypsin; D002118:Calcium