Effects of sulfhydryl groups and oxygen tension on the cell proliferating activity of bovine serum albumin in culture.

Abstract

We reported previously that bovine serum albumin (BSA) has growth promoting activity which depends upon lipids (especially poly-un-saturated fatty acids) bound to the BSA molecule. This activity was proved to depend upon the oxygen tension in the culture environment. The experiment described here shows the relationship between the growth of human diploid fibroblasts in a serum-free, BSA-containing medium and changes in the sulf hy-dryl contents in the medium. When cells (2 × 104 cells/plastic petri dish) were plated in dish (diameter of 35 mm), the sulfhydryl contents of the culture media decreased rapidly, then they increased gradually. Following the increase in the sulfhydryl contents, cell growth at atmospheric oxygen tension declined. But, when the sulfhydryl contents were maintained at a low level by treating BSA with 0.0015 (W/V) % H202 or by adding sylfhydryl compounds to the medium, excellent cell growth was obtained during the period of culture. These results suggest that the number of sulf hydryl groups of albumin present may regulate the equilibrium between BSA-bound fatty acids and free fatty acids in the medium.