Linked Life Data

188467

Source:http://linkedlifedata.com/resource/pubmed/id/188467

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1977-3-21
pubmed:abstractText
GMP synthetase (xanthosine-5'-phosphate: ammonia ligase (AMP-forming), EC 6.3.4.1) from Ehrlich ascites cells was found to be subject to multiple inhibition by its reaction product, PPi, and some analogs of adenosine. PPi and the nucleoside (N) inhibitors were also capable of individually inhibiting this enzyme. Under no conditions did the inhibition appear to be irreversible or "pseudoinactivating" in nature. The individual inhibition by PPi was competitive with respect to ATP (KI = 0.42 mM). Conversely, in the absence of PPi, the binding of N was noncompetitive with ATP, but shifted to a competitive pattern when PPi was present. Furthermore, with the inhibitors in concert, there was an apparent lowering of the KI values for both inhibitors. This data was consistent with either PPi functioning to tighten the binding of N at a noncatalytic site (positive cooperativity) or with PPi actually opening a second binding site for N in addition to the non-catalytic site. Although this study did not distinguish which of these events was occurring, it did reveal that the intensity of the effect of PPi appeared to be constant. That is, for various N inhibitors with a range of independently determined KI values from 26 to 1650 muM, the ratio of their KI values determined in the absence of PPi to the values determined in the presence of PPi was always 38 +/- 1.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0006-3002
pubmed:author
pubmed:issnType
Print
pubmed:day
8
pubmed:volume
452
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
597-607
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Guanosine monophosphate synthetase from Ehrlich ascites cells. Multiple inhibition by pyrophosphate and nucleosides.
pubmed:publicationType
Journal Article