Linked Life Data

1988050

Source:http://linkedlifedata.com/resource/pubmed/id/1988050

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1991-2-27
pubmed:abstractText
The velocity of the oxidative renaturation of reduced ribonuclease A catalyzed by protein disulfide isomerase (PDI) is strongly dependent on the composition of a glutathione/glutathione disulfide redox buffer. As with the uncatalyzed, glutathione-mediated oxidative folding of ribonuclease, the steady-state velocity of the PDI-catalyzed reaction displays a distinct optimum with respect to both the glutathione (GSH) and glutathione disulfide (GSSG) concentrations. Optimum activity is observed at [GSH] = 1.0 mM and [GSSG] = 0.2 mM. The apparent kcat at saturating RNase concentration is 0.46 +/- 0.05 mumol of RNase renatured min-1 (mumol of PDI)-1 compared to the apparent first-order rate constant for the uncatalyzed reaction of 0.02 +/- 0.01 min-1. Changes in GSH and GSSG concentration have a similar effect on the rate of both the PDI-catalyzed and uncatalyzed reactions except under the more oxidizing conditions employed, where the catalytic effectiveness of PDI is diminished. The ratio of the velocity of the catalyzed reaction to that of the uncatalyzed reaction increases as the quantity [GSH]2/[GSSG] increases and approaches a constant, limiting value at [GSH]2/[GSSG] greater than 1 mM, suggesting that a reduced, dithiol form of PDI is required for optimum activity. As long as the glutathione redox buffer is sufficiently reducing to maintain PDI in an active form [( GSH]2/[GSSG] greater than 1 mM), the rate acceleration provided by PDI is reasonably constant, although the actual rate may vary by more than an order of magnitude. PDI exhibits half of the maximum rate acceleration at a [GSH]2/[GSSG] of 0.06 +/- 0.01 mM.
pubmed:grant
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
22
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
613-9
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Catalysis of the oxidative folding of ribonuclease A by protein disulfide isomerase: dependence of the rate on the composition of the redox buffer.
pubmed:affiliation
Verna and Marrs McLean Department of Biochemistry, Baylor College of Medicine, Houston, Texas 77030.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.