Research Information System
JOURNAL OF FOOD BIOCHEMISTRY, vol.28, no.2, pp.155-168, 2004 (SCI-Expanded)
Glucose-6-phosphate dehydrogenase (D-glucose-6-phosphate: NADP(+) oxidoreductase, EC 1.1.1.49; G6PD) was purified from coriander (Coriandrum sativum) leaves; the kinetic behavior and some properties of the enzyme were also investigated. The purification was done at 4C and involved two steps: ammonium sulfate fractionation, and DEAF-Sephadex A50 ion exchange chromatography. The enzyme was obtained with a yield of 26.4% and had a specific activity of 1.826 U/mg protein. Optimum pH, stable pH, optimum temperature, molecular weight, K-M and V-max values for NADP(+) and glucose 6-phosphate (G6-P) were also determined. The overall purification was about 74 fold. SDS-PAGE of the purified enzyme showed a single band. Enzymatic activity was spectrophotometrically measured according to Beutler's method at 340 nm. The molecular mass was estimated to be 74.4 kDa by SDS-PAGE and 73.2 kDa by Sephadex G-200 gel filtration column chromatography. The enzyme had an optimum pH at 8.5 and was stable at pH 8.0 in 0.1 M Tris-HCl buffer. The optimum temperature was at 30C. The KM values for NADP(+) and G6-P were 0.026 mM and 0.116 mM, respectively. The V-max values for these substrates were 0.035 EU/mL and 0.038 EU/mL, respectively.