Glutaminase of Escherichia coli

Studies on the exchange of oxygen catalyzed by Escherichia coli glutaminase between water and substrates are reported. The rates of the virtual hydrolysis of glutamic acid, i.e. the exchange of 18 O between water and the γ-carboxyl oxygen atoms, allow determination of the K m and k cat values for t...

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Bibliographic Details
Published in:The Journal of biological chemistry 1968-03, Vol.243 (5), p.864-869
Main Authors: Hammer, R A, Hartman, S C
Format: Article
Language:English
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Summary:Studies on the exchange of oxygen catalyzed by Escherichia coli glutaminase between water and substrates are reported. The rates of the virtual hydrolysis of glutamic acid, i.e. the exchange of 18 O between water and the γ-carboxyl oxygen atoms, allow determination of the K m and k cat values for this substrate. These values are 2.9 m m and 5080 sec -1 , respectively, at 25° and pH 5.0. The k cat , which is shown to be the number of complete catalytic cycles of the enzyme per sec, is the highest of any known substrate of this enzyme, and among the highest for an enzyme-catalyzed reaction of a carboxylic derivative. Glutaminase does not catalyze exchange between the γ-carbonyl oxygen atoms of glutamine and water.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)93596-9