2bd2 | pdb_00002bd2
Porcine pancreatic elastase complexed with beta-casomorphin-7 and Arg-Phe at pH 5.0
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Overview
Mass spectrometric screening reveals that an unmodified natural heptapeptide--human beta-casomorphin-7, an internal sequence of human beta-casein that possesses opioid-like activity--reacts with porcine pancreatic elastase to form an unusually stable acyl-enzyme complex at low pH. X-ray crystallographic analysis (to 1.9 A resolution) at pH 5 shows continuous electron density linking the C-terminal isoleucine of beta-casomorphin-7 to Ser 195 through an ester bond. The structure reveals a well defined water molecule (Wat 317), equidistant between the carbon of the ester carbonyl and N epsilon 2 of His 57. Deprotonation of Wat 317 will produce a hydroxide ion positioned to attack the ester carbonyl through the favoured Burgi-Dunitz trajectory.
About this Structure
2BD2 is a Single protein structure of sequence from Sus scrofa with CA, SO4, ARG and PHE as ligands. Active as Pancreatic elastase, with EC number 3.4.21.36 Full crystallographic information is available from OCA.
Reference
Structure of a specific acyl-enzyme complex formed between beta-casomorphin-7 and porcine pancreatic elastase., Wilmouth RC, Clifton IJ, Robinson CV, Roach PL, Aplin RT, Westwood NJ, Hajdu J, Schofield CJ, Nat Struct Biol. 1997 Jun;4(6):456-62. PMID:9187653
Page seeded by OCA on Thu Feb 21 16:36:34 2008
