Linked Life Data

2021608

Source:http://linkedlifedata.com/resource/pubmed/id/2021608

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
17
pubmed:dateCreated
1991-5-31
pubmed:abstractText
Proteolytic modification of tryptophan synthase holo-beta 2-subunit from Escherichia coli at the C-terminal side of E-296 leads to an active species (E-296-nicked holo-beta 2) capable of interacting with alpha-subunits. Although this heterologous subunit interaction is rather weak, it induces an increase in catalytic efficiency in E-296-nicked holo-beta 2 by a factor of about 150. Correspondingly, enzymatic activity of alpha-subunits is enhanced 180-fold. This is in striking contrast to the findings from earlier reports which demonstrated that proteolytic derivatives modified at other positions in the "hinge region" embedded in the C-domain of the beta 2-subunit (K-272, R-275, and K-283) are enzymatically inactive and cannot associate with alpha-subunits. The equilibrium binding curve for the cofactor pyridoxal 5'-phosphate to E-296-nicked apo-beta 2 is hyperbolic (i.e., noncooperative), yielding an apparent microscopic dissociation constant, Kd, of 5 x 10(-6) M. This value closely resembles the low-affinity dissociation constant of cooperative cofactor binding to the native beta 2-subunit, indicating that the conformational interactions between structural domains in the modified beta-protein seem to be disturbed considerably.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
30
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
4173-9
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Limited proteolysis of the beta 2-dimer of tryptophan synthase yields an enzymatically active derivative that binds alpha-subunits.
pubmed:affiliation
Institut für Physiologische Chemie, Universität Witten/Herdecke, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't