Linked Life Data

9210469

Source:http://linkedlifedata.com/resource/pubmed/id/9210469

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1997-8-4
pubmed:abstractText
Oxidized, free, stable phosphoribulokinase from Chlamydomonas reinhardtii was almost completely devoid of catalytic activity (0.06 s(-1)/site). However, when it was bound to glyceraldehyde-3-phosphate dehydrogenase from the same organism, it displayed significant activity (3.25 s(-1)/site). Moreover, this complex tended to spontaneously dissociate upon dilution; the isolated phosphoribulokinase activity increased up to 56 s(-1)/site, subsequently decreased, and finally became almost completely inactive. Its intrinsic kinetic properties (Km and k(cat)) changed with the variation of the overall activity. These effects were paralleled by changes of conformation of the enzyme as revealed by fluorescence analysis. A model is proposed that allows quantitative expression of the dynamics of the dissociation of the oxidized bienzyme complex and the effects of either of the two substrates, ATP and ribulose 5-phosphate, on this dissociation process. Whereas ATP destabilized the complex and promoted its dissociation, ribulose 5-phosphate tended to stabilize this complex. Inactive, stable, oxidized phosphoribulokinase may form a complex with glyceraldehyde-3-phosphate dehydrogenase regaining its catalytic activity. In this case, glyceraldehyde-3-phosphate dehydrogenase acts in a manner similar, but not identical to a chaperonin. The information content of the phosphoribulokinase gene, as defined by the sequence of its base pairs, was therefore not sufficient to specify full enzyme activity. It needed the presence of glyceraldehyde-3-phosphate dehydrogenase to give the oxidized phosphoribulokinase a conformation competent for its activity. The potential biological significance of these effects remains to be discovered.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
246
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
85-91
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed-meshheading:9210469-Adenosine Triphosphate, pubmed-meshheading:9210469-Animals, pubmed-meshheading:9210469-Chlamydomonas reinhardtii, pubmed-meshheading:9210469-Chloroplasts, pubmed-meshheading:9210469-Enzyme Activation, pubmed-meshheading:9210469-Enzyme Stability, pubmed-meshheading:9210469-Fluorescence, pubmed-meshheading:9210469-Glutathione, pubmed-meshheading:9210469-Glyceraldehyde-3-Phosphate Dehydrogenases, pubmed-meshheading:9210469-Kinetics, pubmed-meshheading:9210469-Models, Chemical, pubmed-meshheading:9210469-Multienzyme Complexes, pubmed-meshheading:9210469-Oxidation-Reduction, pubmed-meshheading:9210469-Phosphotransferases (Alcohol Group Acceptor), pubmed-meshheading:9210469-Protein Conformation, pubmed-meshheading:9210469-Ribulosephosphates, pubmed-meshheading:9210469-Tryptophan
pubmed:year
1997
pubmed:articleTitle
Memory and imprinting effects in multienzyme complexes--II. Kinetics of the bienzyme complex from Chlamydomonas reinhardtii and hysteretic activation of chloroplast oxidized phosphoribulokinase.
pubmed:affiliation
Institut Jacques Monod, Université Paris VII, France.
pubmed:publicationType
Journal Article