Linked Life Data

9488696

Source:http://linkedlifedata.com/resource/pubmed/id/9488696

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
10
pubmed:dateCreated
1998-4-7
pubmed:abstractText
Nucleoside-diphosphate kinases (NDKs) catalyze the transfer of gamma-phosphoryl groups from NTPs via an active site histidine to NDPs using a ping-pong mechanism. We have used the change of intrinsic tryptophan fluorescence that occurs upon phosphorylation of NDK to measure the rates of phosphorylation and dephosphorylation with a range of nucleotides and nucleotide analogues. For natural nucleotides, the rates of phosphorylation and dephosphorylation were linearly dependent upon nucleotide concentration until they became too fast to measure. The second order rate constants for phosphorylation by natural NTPs varied between 0.7 and 13 x 10(6) M-1 s-1. Dephosphorylation by NDPs was 2-3-fold faster than the corresponding phosphorylation reaction, and dephosphorylation by dNDPs was 3-4-fold slower than the equivalent NDPs. In all cases, second order rate constants were highest for guanine followed by adenine and lowest for cytosine nucleotides. NDK also catalyzes the transfer of thiophosphate from adenosine 5'-O-(thiotriphosphate) (ATPgammaS) and guanosine 5'-O-(thiotriphosphate) (GTPgammaS) to NDP, but at (1)/(1000) of the equivalent phosphoryl transfer rates. In this case, the observed rate constants of phosphorylation and dephosphorylation were hyperbolically dependent on nucleotide concentration. Thiophosphorylation by ATPgammaS and GTPgammaS occurred with kmax of 2.8 and 1.35 s-1 and Kd of 145 and 36 muM respectively. For dethiophosphorylation by a range of NDPs, kmax was in the range of 5-30 s-1, whereas Kd varied between 0.16 and 3.3 mM. Guanine had the lowest Kd values, and cytosine had the highest. The data are consistent with fast reversible binding of the nucleotide followed by the rate-limiting phosphoryl transfer. Thiophosphates change only the rate of the phosphoryl transfer step, whereas both events are influenced by the base. Modification at the 2'-hydroxyl of ribose has only a small effect, while the overall rate of phosphoryl transfer is reduced 1000-fold by modification at the 3'-ribose.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
6
pubmed:volume
273
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5662-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Substrate specificity of human nucleoside-diphosphate kinase revealed by transient kinetic analysis.
pubmed:affiliation
Max-Planck Institut fur biophysikalische Chemie, Abteilung Molekulare Genetik, D-37070 Gottingen, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't