Publication Date:
1992-03-06
Description:
Trypsin (Tr) and chymotrypsin (Ch) have similar tertiary structures, yet Tr cleaves peptides at arginine and lysine residues and Ch prefers large hydrophobic residues. Although replacement of the S1 binding site of Tr with the analogous residues of Ch is sufficient to transfer Ch specificity for ester hydrolysis, specificity for amide hydrolysis is not transferred. Trypsin is converted to a Ch-like protease when the binding pocket alterations are further modified by exchange of the Ch surface loops 185 through 188 and 221 through 225 for the analogous Tr loops. These loops are not structural components of either the S1 binding site or the extended substrate binding sites. This mutant enzyme is equivalent to Ch in its catalytic rate, but its substrate binding is impaired. Like Ch, this mutant utilizes extended substrate binding to accelerate catalysis, and substrate discrimination occurs during the acylation step rather than in substrate binding.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Hedstrom, L -- Szilagyi, L -- Rutter, W J -- DK21344/DK/NIDDK NIH HHS/ -- New York, N.Y. -- Science. 1992 Mar 6;255(5049):1249-53.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Hormone Research Institute, University of California, San Francisco 94143-0534.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/1546324" target="_blank"〉PubMed〈/a〉
Keywords:
Acylation
;
Amino Acid Sequence
;
Base Sequence
;
Binding Sites
;
Chymotrypsin/*chemistry/metabolism
;
Hydrolysis
;
Kinetics
;
Models, Molecular
;
Molecular Sequence Data
;
Molecular Structure
;
Mutagenesis, Site-Directed
;
Protein Conformation
;
Substrate Specificity
;
Trypsin/*chemistry/genetics/metabolism
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
,
Chemistry and Pharmacology
,
Computer Science
,
Medicine
,
Natural Sciences in General
,
Physics
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