Abstract
A simple and rapid method for the determination of glycerol-3-phosphate dehydrogenase (EC, 1. 1. 1. 8, GPD) isoenzymes in human tissues was examined using Cellogel membrane electrophoresis. An LL isoenzyme of glycerol-3-phosphate dehydrogenase was partially isolated from human heart muscle and determined apparent Km value for NADH.Then actMties and isoenzymes of glycerol-3-phosphate dehydrogenase and lactate dehydrogenase in 100000xG supernatant were measured in human tissues. The glycerol-3-phosphate dehydrogenase apPeared to form dimeric combinations of two different subunits, H and L, and formed three isoenzymes HH, HL and LL. The HH form represents the major heart isoenzy me and LL represents the liver. These results are in agreement with the report of McGinnis and Vellis. in skeletal muscle such as femoral and rectal abdominal muscle and kidney, the LL isoenzyme was more than 80% of total activity and a hybrid form HL was about 20%.
The apparent Km value for NADH of LL form was measured to be 7.8μM which value was lower than that of lactate dehydrogenase (LD) isoenzymes.The calculated activity ratios, LD (Total) /GPD (LL), LD (H-subunit) /GPD (LL) and LD (M-subunit) /GPD (LL), of rectal abdominal muscles and livers were lower than LD (H-subunit) /GPD (LL) of femoral muscies.These results indicate the abnormal participation of the glyCerol-3-phosphate dehydrogenase to the reoxidation of NADH in the muscle and the liver under anaerobic conditions.
