Regulation Of Glutaminase In E-Coli - Metabolite Control

Escherichia coli has been shown to possess two glutaminases A and B, with pH optima at 5 and 7 respectively. Glutaminase B, the subject of this communication, is a cold labile enzyme which is subject to regulation by many metabolites. Preincubation of the enzyme at 4° C with di- and tri-carboxylic acids and cyclic 3′, 5′ AMP results in a marked activation of catalytic activity while preincubation with adenine nucleoside di- and tri-phosphates leads to inactivation. Metabolite regulation of glutaminase B prevents the operation, with glutamine synthetase, of a futile cycle in which the cellular energy stores might be consumed.