Structure of a specific acyl-enzyme complex formed between β-casomorphin-7 and porcine pancreatic elastase

被引：0

作者：

Rupert C. Wilmouth

Ian J. Clifton

Carol V. Robinson

Peter L. Roach

Robin T. Aplin

Nicholas J. Westwood

Janos Hajdu

Christopher J. Schofield

机构：

[1] The Oxford Centre for Molecular Sciences,Department of Biochemistry

[2] The Dyson Perrins Laboratory,undefined

[3] Laboratory of Molecular Biophysics,undefined

[4] Uppsala University,undefined

来源：

Nature Structural Biology | 1997年 / 4卷

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摘要：

Mass spectrometric screening reveals that an unmodified natural heptapeptide—human β-casomorphin-7, an internal sequence of human β-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 Å resolution) at pH 5 shows continuous electron density linking the C-terminal isoleucine of β-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 Nε2 of His 57. Deprotonation of Wat 317 will produce a hydroxide ion positioned to attack the ester carbonyl through the favoured Bürgi-Dunitz trajectory.

引用

页码：456 / 462

页数：6