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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
6
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pubmed:dateCreated |
1997-7-14
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pubmed:abstractText |
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 Bürgi-Dunitz trajectory.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Jun
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pubmed:issn |
1072-8368
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
4
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
456-62
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pubmed:dateRevised |
2006-11-15
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pubmed:meshHeading |
pubmed-meshheading:9187653-Animals,
pubmed-meshheading:9187653-Crystallography, X-Ray,
pubmed-meshheading:9187653-Endorphins,
pubmed-meshheading:9187653-Humans,
pubmed-meshheading:9187653-Kinetics,
pubmed-meshheading:9187653-Mass Spectrometry,
pubmed-meshheading:9187653-Models, Molecular,
pubmed-meshheading:9187653-Pancreatic Elastase,
pubmed-meshheading:9187653-Peptide Fragments,
pubmed-meshheading:9187653-Peptides,
pubmed-meshheading:9187653-Protein Conformation,
pubmed-meshheading:9187653-Substrate Specificity,
pubmed-meshheading:9187653-Swine
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pubmed:year |
1997
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pubmed:articleTitle |
Structure of a specific acyl-enzyme complex formed between beta-casomorphin-7 and porcine pancreatic elastase.
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pubmed:affiliation |
Oxford Centre for Molecular Sciences, UK.
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pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't
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