Catalytic properties of glucose-6-phosphate dehydrogenase from pea leaves.
A homogeneous preparation of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) with a specific activity of 3.88 U/mg protein was isolated from pea (Pisum sativum L.) leaves. The molecular mass of the G6PDH is 79 +/- 2 kD. According to SDS-PAGE, the molecular mass of the enzyme subunit is 40 +/- 3 kD. The Km values for glucose-6-phosphate and NADP are 2 and 0.5 mM, respectively. The enzyme has a pH optimum of 8.0. Mg2+, Mn2+, and Ca2+ activate the enzyme at concentrations above 1 mM. Galactose-6-phosphate and fructose-6-phosphate inhibit the G6PDH from pea leaves. Fructose-1, 6-bisphosphate and galactose-1-phosphate are enzyme activators. NADPH is a competitive inhibitor of the G6PDH with respect to glucose-6-phosphate (Ki = 0.027 mM). ATP, ADP, AMP, UTP, NAD, and NADH have no effect on the activity of the enzyme.
Semenikhina
A V
AV
Department of Plant Physiology and Biochemistry, Voronezh State University, Voronezh, 394693, Russia. root@bc.vsu.ru
Popova
T N
TN
Matasova
L V
LV
D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D005954:Glucosephosphate Dehydrogenase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D018532:Pisum sativum / Q000201:enzymology*; D018515:Plant Leaves / Q000201:enzymology
D005954:Glucosephosphate Dehydrogenase