Author(s): Siham Abdalmohsen Al Kadeeb and Mona Salah Al-Tami
Article publication date: 2005-06-01
Vol. 23 No. 2 (yearly), pp. 62-68.
127
Keywords
Alternaria chlamydospora, L-serine-glutamate, Characterization and properties
Abstract
Cell-free extracts of Alternaria chlamydospora contained only one L-serine transaminase activity. The enzyme was L-serine-glutamate transaminase (EC 2.6.1.52) which catalyzed the formation of 3-hydroxy pyruvate and glutamate from L alpha-serine and alpha-ketoglutarate. The enzyme had optimum activity at pH 8 and the optimal temperature of the enzyme was 40°C. The transamination reaction catalyzed by L-serine- glutamate transaminase was found to be irreversible. The enzyme was thermolabile. Km of Alternaria chlamydospora enzyme for L-serine and alpha-ketoglutarate were calculated and found to be 13.33 and 6.66 mm respectively. The activity of L-glutamate transaminase of Alternaria chlamydospora was stimulated by the addition of pyridoxal phosphate, whereas hydroxylamine inhibited it. The inhibition by hydroxylamine was overcome with pyridoxal phosphate.