Linked Life Data

1892833

Source:http://linkedlifedata.com/resource/pubmed/id/1892833

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
38
pubmed:dateCreated
1991-10-23
pubmed:abstractText
The fate of the alpha-hydrogen of mandelate in the reaction catalyzed by mandelate racemase has been investigated by a mass spectroscopic method. The method entails the incubation of (R)- or (S)-[alpha-1H]mandelate in buffered D2O to a low extent of turnover (about 5-8%), esterification of the resulting mixture of mandelates with diazomethane, derivatization of the methyl esters with a chiral derivatizing agent, and quantitation of the isotope content of the alpha-hydrogen of both substrate and product by gas chromatography/mass spectrometric analysis. No significant substrate-derived alpha-protium was found in the product for racemization in either direction. In addition, in the (R) to (S) direction almost no exchange (less than or equal to 0.4%) of the alpha-hydrogen in the remaining (R) substrate pool occurred, but in the (S) to (R) direction 3.5-5.1% exchange of the alpha-hydrogen in the remaining substrate (after 5.1-7.2% net turnover) was found. Qualitatively similar results were obtained in the (S) to (R) direction in H2O when (S)-[alpha-2H]mandelate was used as substrate. In other experiments, an overshoot in the progress curve was observed when the racemization of either enantiomer of [alpha-1H]mandelate in D2O was monitored by following the change in ellipticity of the reaction mixture; the magnitude of the overshoot was greater in the (R) to (S) than in the (S) to (R) direction. All of the available data indicate that the reaction catalyzed by mandelate racemase proceeds by a two-base mechanism, in contrast to earlier proposals.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
24
pubmed:volume
30
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
9255-63
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1991
pubmed:articleTitle
Mechanism of the reaction catalyzed by mandelate racemase. 1. Chemical and kinetic evidence for a two-base mechanism.
pubmed:affiliation
Department of Pharmaceutical Chemistry, University of California, San Francisco 94143.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't