[Reactions of decarboxylated and side transamination during interaction of glutamate decarboxylase from Escherichia coli with substrate analogs, modified through C3 and C4 atoms]. / Reaktsii dekarboksilirovaniia i pobochnogo transaminirovaniia pri vzaimodeistvii glutamatdekarboksilazy iz Escherichia coli s analogami substrata, modifitsirovannymi po atomam C3 i C4.

The interaction of glutamate decarboxylase with the aspartate and glutamate analogues modified at C3 and C4 was studied. 3-Arsonoalanine, 3-phosphonoalanine, 2-amino-4-arsonobutyric acid, 2-amino-4-phosphonobutyric acid, a mixture of diastereoisomers of 4-(methylthio) glutamic acid and erythro-4-(methylthio) glutamic acid were shown to be poor substrates for the enzyme. Their decarboxylation was accompanied by transamination of the coenzyme (PLP) to pyridoxamine phosphate (PMP) which reversibly inactivated the enzyme. With arsonoalanine only part of PLP was converted into PMP and another part irreversibly formed a complex. 4-(Methylsulfonyl)-L-glutamic and 4-[(phenyl)(hydroxy)phosphoryl]-L-glutamic acids did not react with the glutamate decarboxylase.

The interaction of glutamate decarboxylase from Escherichia coli with substrate analogues modified at C-3 and C-4.

The interaction of glutamate decarboxylase with the aspartate analogues 3-arsonoalanine and 3-phosphonoalanine, with the glutamate analogues 2-amino-4-arsonobutyric acid and 2-amino-4-phosphonobutyric acid, and with 4-(methylthio)-L-glutamic acid, both as a mixture of diastereoisomers and as the (2S,4R)-form, was studied. All these analogues were poor substrates for the enzyme and only weak inhibitors. Their decarboxylation was accompanied by transamination of the enzyme-bound pyridoxal phosphate (PLP) to pyridoxamine phosphate (PMP), thus inactivating the decarboxylase. With arsonoalanine only part of the PLP was converted into PMP.