Isolation and Characterization of Sorbitol Dehydrogenase from Human Plasma

The research is concerned with the isolation of sorbitol dehydrogenase (SDH) from the normal human plasma using different biochemical techniques. The results of filtration chromatography on sephadex G-100, that the solution contains proteinous precipitate which was resulted by ammonium sulfate precipitation after dialysis. The second bunch () shows high effectiveness of the enzyme. The number of purification of the second bunch () is (8) times. Furthermore, the approximate molecular weight of the partially purified (SDH), bunch, () using gel filtration was found to be (38672) Dalton. Optimum conditions were obtained in this research. The results showed that the enzyme works in the buffer solution using (100l) of triethanolamine as a buffer, in pH (7), and the incubation temperature was (40C), The incubation time was (1min.) and (1.5M) of D-Fructose as a substrate was used. By using lineweaver-Burk plot, it was found that the maximum velocity (Vmax) was (0.53mol) and Michaelis constant (Km) was (0.92M). The effect of some chemical compounds on (SDH) activity was also studied. Some compounds have an activator effect like (EDTA, Mg, Zn), whereas sodium floride )NaF) showed uncompetitive inhibition on the activity of the enzyme at a concentration (3 m mol /L).