Linked Life Data

9132

Source:http://linkedlifedata.com/resource/pubmed/id/9132

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
1976-11-21
pubmed:abstractText
Two classes of sulfhydryl groups in histidine decarboxylase from Lactobacillus 30 a can be differentiated by their reaction with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Five cysteinyl residues (class I) of the native enzyme are titrated by DTNB as the pH of the reaction medium is increased from 6.5 to 7.5; the pH-rate profile for their reaction is described by a pKa of 9.2. An additional five thiol groups (class II) are titrated only when denaturing agents are added above neutral pH. Histidine decarboxylase is completely inactivated by DTNB in a kinetically second-order process (Kapp = 660 +/- 20 M-1 min-1 at pH 7.6 and 25 degrees C) which occurs coincident with and at the same rate as modification of the five class-I SH groups of the enzyme, i.e., one thiol group per pyruvoyl prosthetic group. The competitive inhibitors, histamine and imidazole, markedly enhanced the reactivity of these cysteinyl residues toward DTNB; this enhancement is accompanied by a concomitant increase in the rate of inactivation. A single SH group in each of the five catalytic units of histidine decarboxylase is thus implicated as being critical for the expression of enzymatic activity.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
21
pubmed:volume
15
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4175-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Histidine decarboxylase of Lactobacillus 30a: function and reactivity of sulfhydryl groups.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.