Linked Life Data

8308029

Source:http://linkedlifedata.com/resource/pubmed/id/8308029

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1994-3-17
pubmed:abstractText
The structure of the acylenzyme intermediate in the hydrolysis of the specific spin-label ester substrate methyl N-(2,2,5,5-tetramethyl-1-oxypyrrolinyl-3-carbonyl)-L-tryptophan ate and its fluoro analogs catalyzed by alpha-chymotrypsin (EC 3.4.21.1) has been determined by electron nuclear double resonance (ENDOR) and molecular modeling methods. By a combination of kinetic and cryoenzymological methods, we have established conditions to stabilize the spin-labeled acylenzyme reaction intermediate. Proton ENDOR features specific for the substrate were assigned on the basis of specific deuteration. From the observed ENDOR shifts for protons and fluorines that correspond to principal hyperfine coupling components, the dipolar hyperfine coupling contributions were calculated to estimate electron-nucleus distances. With these dipolar separations as constraints, conformations of the substrate both free in solution and in the active site of alpha-chymotrypsin were determined by molecular graphics analysis. Comparison of the conformation of the bound substrate to that of the free substrate showed that formation of the acylenzyme requires significant torsional alteration in substrate structure. The structural relationships between active-site residues and the substrate in its ENDOR-assigned conformation are examined with respect to the requirements of stereoelectronic rules for formation and breakdown of the acylenzyme species.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
11
pubmed:volume
269
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4577-86
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Structure at the active site of an acylenzyme of alpha-chymotrypsin and implications for the catalytic mechanism. An electron nuclear double resonance study.
pubmed:affiliation
Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.