We examined the effects on alanine aminotransferase and aspartate aminotransferase of different aminothiols (L-cysteine, D-cysteine, cysteamine, L-cysteine ethyl ester, L-cysteine methyl ester) and several vitamin B-6 derivatives (pyridoxal, pyridoxamine, pyridoxol, pyridoxol 5'-phosphate), before and after treatment with KOCN, which transforms these molecules into the corresponding carbamoyl derivatives. Only GPT, and not GOT, was specifically inhibited by L-cysteine and, to a lesser extent, by D-cysteine. The association reaction: PLP + apo GPT<-->holo GPT was inhibited by the vitamin B-6 derivatives, and this inhibition was prevented by pretreatment of the vitamin B-6 derivatives with KOCN. All the observed effects occurred at pH 7, 37 degrees C, at mM and even lower concentrations of reagents. Hence, they all potentially play a physiological role, in the regulation of the PLP dependent enzymes and of the vitamin B-6 levels in the cell.
Pagani, R., Leoncini, R., Terzuoli, L., Pizzichini, M., Marinello, E. (1994). The Regulation of Alanine and Aspartate Aminotransferase by different aminothiols and by Vitamin B6 Derivatives. BIOCHIMICA ET BIOPHYSICA ACTA, 1204(2), 250-256 [10.1016/0167-4838(94)90015-9].
The Regulation of Alanine and Aspartate Aminotransferase by different aminothiols and by Vitamin B6 Derivatives
Pagani R.;Leoncini R.;Terzuoli L.;Pizzichini M.;Marinello E.
1994-01-01
Abstract
We examined the effects on alanine aminotransferase and aspartate aminotransferase of different aminothiols (L-cysteine, D-cysteine, cysteamine, L-cysteine ethyl ester, L-cysteine methyl ester) and several vitamin B-6 derivatives (pyridoxal, pyridoxamine, pyridoxol, pyridoxol 5'-phosphate), before and after treatment with KOCN, which transforms these molecules into the corresponding carbamoyl derivatives. Only GPT, and not GOT, was specifically inhibited by L-cysteine and, to a lesser extent, by D-cysteine. The association reaction: PLP + apo GPT<-->holo GPT was inhibited by the vitamin B-6 derivatives, and this inhibition was prevented by pretreatment of the vitamin B-6 derivatives with KOCN. All the observed effects occurred at pH 7, 37 degrees C, at mM and even lower concentrations of reagents. Hence, they all potentially play a physiological role, in the regulation of the PLP dependent enzymes and of the vitamin B-6 levels in the cell.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
https://hdl.handle.net/11365/37742
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