Linked Life Data

6562904

Source:http://linkedlifedata.com/resource/pubmed/id/6562904

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1984-7-20
pubmed:abstractText
The benzoxazinones 2-ethoxy-4H-3,1- benzoxazin -4-one (1a) and 2-(trifluoromethyl)-4H-3,1- benzoxazin -4-one (1d) inactivate chymotrypsin. The inactivation is stoichiometric and proceeds with rate constants of 7 X 10(5) M-1 min-1 and greater than 4 X 10(6) M-1 min-1, respectively. The inactivated enzyme recovers catalytic activity slowly, k = 2.3 X 10(-3) min-1 and 3.7 X 10(-2) min-1 (pH 7.1). When the enzyme regains catalytic activity, 2-[N-(ethoxycarbonyl)amino]benzoic acid is released from enzyme inactivated with 1a and N-(trifluoroacetyl)anthranilic acid from enzyme inactivated with 1d. The mechanism of inactivation involves attack of the active site serine on the C-4 carbonyl of the inactivator which leads to ring opening and formation of an ortho-substituted benzoylchymotrypsin , which hydrolyzes slowly due to electron releasing ability of the substituents. The rate of hydrolysis of the benzoylchymotrypsin from 1a or 1d is in close agreement with those predicted from the Hammett parameters (sigma, rho) for hydrolysis of their para-substituted analogues [ Caplow , M., & Jencks , W. P. (1962) Biochemistry 1, 883-893]. The inactivation of chymotrypsin by 2-methyl-4H-3,1- benzoxazin -4-one (1b) is an equilibrium process (kinact = 1 X 10(4) M-1 min-1 and Keq = 2 X 10(6) M-1). Formation of a benzoylchymotrypsin is demonstrated by spectral changes and methanol trapping. The benzoylchymotrypsin can also decay by direct hydrolysis to N- acetylanthranilic acid.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1753-9
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Suicide inactivation of chymotrypsin by benzoxazinones.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.