Characterization of a stable isoenzyme of malate dehydrogenase (MDH1) from blood stream Trypanosoma vivax

International Journal of Physical Sciences

Wurochekke¹ 

关键词: Malate dehydrogenase;    Trypanosoma vivax;    isoenzyme.;   

DOI  :  

学科分类：物理（综合）

来源: Academic Journals

【 摘 要 】

MDH1, isoenzyme of malate dehydrogenase from blood streamTrypanosoma vivaxwas characterized. The enzyme was active over a broad pH and temperature range with optimal values of 5.0 and 35oC respectively. The energy of activation was 20.58kj/mol and the pKa values were 6.8 and 7.8 implicating ionizable groups at the catalytic site. Kinetic studies conducted in the direction of oxaloacetate reduction gave KMof 0.56 and 0.3 mM and Vmaxof 4.6 and 3.2 µmol./ min/mg for oxaloacetate and NADH respectively. Similarly, in the reverse reaction, malate had KMof 0.16 Mm and Vmaxof 57 µmol./min/mg, and KMand Vmaxof NAD+were 0.1 5 mM and 48 µmol./min/mg. The enzyme was inhibited competitively with NAD+as a product inhibitor and uncompetitive with malate. The product inhibition studies suggest bi-bi ordered sequential mechanism of catalysis. SomeTCA cycle intermediates also inhibited to different extent the activity of the enzyme.

【 授权许可】

CC BY