1978 Volume 6 Issue 1 Pages 63-66
The physiological significance of serum nonspecific carboxyl esterase (tributylin hydrolase) is not clearly understood. Cucuianu et al. reported that esterase was closely related to triglyceride metabolism. Furthermore, Okuda et al. reported that nonspecific esterase might be converted to lipase (ediol hydrolysis activity) in rat liver. To clarify the relationship between serum nonspecific esterase and triglyceride metabolism, such as hypertriglyceridemia and triglyceride hydrolysis in arterial wall, the experiments were carried out in humans and rats.
In the clinical investigation of 500 farmers at Yoshida Machi in Ehime prefecture, serum triglyceride concentrations of the farmers increased after a period of sprinkling agricultural pesticide. Serum nonspecific carboxyl esterase decreased reciprocally with the increase in triglyceide concentration. These results suggest that serum nonspecific esterase might play a role of triglyceride hydrolysis. When serum nonspecific esterase, which was purified by the method of (NH3)2 SO4 fractionation, Sephadex G-200 and DEAE Sephadex A-50 column chromatography to show a single band of protein in disc electrophoresis, was incubated with slices of rat aorta which had been treated with heparin to remove lipase, a greater extent of lipase (triolein hydrolase) activity was observed than that of the heparin treated aorta and the same extent as that of none treated aorta. Serum nonspecific esterase had no effect when it was treated in boiling water. The same results were confirmed not only chemically but also histochemically.
These results suggested that serum nonspecific carboxyl esterase might be converted to lipase in aorta.
Further studies are now in progress to clarify the relationship between nonspecific carboxyl esterase and lipase, such as localization of nonspecific esterase and lipase in the subcellular fraction, and immunological identification of nonspecific esterase and lipase.
1) Cucuianu, M. et al.: Clin. Chem. Acta, 59: 19 (1975).
2) Okuda, H. & Fuji, S.: J. Biochem., 64: 377 (1968).
