Purification and Kinetic Properties of 6-Phosphogluconate
Dehydrogenase from Rat Small Intestine |
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Authors: | Deniz?Ceyhan Ali?Dani?an I?Hamdi???ü? Email author" target="_blank">Nazmi??zerEmail author |
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Institution: | (1) Department of Biochemistrry, Faculty of Medicine, Hacettepe University, 06100 Ankara, Turkey |
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Abstract: | 6-Phosphogluconate dehydrogenase (6PG) was purified from rat small intestine with 36% yield and a specific activity of 15 U/mg.
On SDS/PAGE, one band with a mass of 52 kDa was found. On native PAGE three protein and two activity bands were observed.
The pH optimum was 7.35. Using Arrhenius plots, Ea, ΔH, Q10 and Tm for 6PGD were found to be 7.52 kcal/mol, 6.90 kcal/mol, 1.49 and 49.4°C, respectively. The enzyme obeyed “Rapid Equilibrium
Random Bi Bi” kinetic model with Km values of 595 ± 213 μM for 6PG and 53.03±1.99 μM for NADP. 1/Vm versus 1/6PG and 1/NADP plots gave a Vm value of 8.91±1.92 U/mg protein. NADPH is the competitive inhibitor with a Ki of 31.91±1.31 μM. The relatively small Ki for the 6PGD:NADPH complex indicates the importance of NADPH in the regulation of the pentose phosphate pathway through G6PD
and 6PGD. |
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Keywords: | Ea glucose-6-phosphate dehydrogenase Δ H Ki values NADPH inhibition pH optimum purification Q10 rat small intestine |
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