Linked Life Data

2831952

Source:http://linkedlifedata.com/resource/pubmed/id/2831952

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1988-4-28
pubmed:abstractText
The number of peptide binding sites of prolyl 4-hydroxylase was manipulated with the peptide photoaffinity label N-(4-azido-2-nitrophenyl)glycyl-(Pro-Pro-Gly)5, and the effect on hydroxylation of the relatively short peptide substrate (Pro-Pro-Gly)5 and of the long natural substrate procollagen was studied. With (Pro-Pro-Gly)5 as a substrate, a linear relation was found between enzyme activity and the amount of covalently bound photoaffinity label, approximately 50% inactivation being reached at 1 mol of label/mol of enzyme. No difference in Km value for (Pro-Pro-Gly)5 was detected between unlabeled and partially labeled enzyme preparations. These results indicate that enzyme molecules with only one free active site hydroxylated the synthetic substrate (Pro-Pro-Gly)5 with the same Km and at half the rate of native enzyme. In contrast, with procollagen as a substrate a 5-10-fold increase in Km was found with the fraction of enzyme containing only one free active site, as compared to the Km for procollagen with nonlabeled enzyme. This finding is explained by an enzyme-kinetic model based on a processive action of the two peptide substrate binding sites of prolyl 4-hydroxylase, preventing dissociation of the enzyme-substrate complex between successive hydroxylations of a long peptide with multiple substrate sites. Such a mechanism leads to a low Km for a long peptide by overcoming the diffusional constraints on the rate of association between the enzyme and the individual substrate sites.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
12
pubmed:volume
27
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
150-5
pubmed:dateRevised
2000-12-18
pubmed:meshHeading
pubmed:year
1988
pubmed:articleTitle
Processive action of the two peptide binding sites of prolyl 4-hydroxylase in the hydroxylation of procollagen.
pubmed:affiliation
Laboratory of Biochemistry, University of Amsterdam, The Netherlands.
pubmed:publicationType
Journal Article