Ascorbate-dependent differences in the hydroxylation of proline and lysine in collagen synthesized by 3T6 fibroblasts in culture

Abstract

The total incorporation of proline and lysine into proteins, and into collagen, is unaffected by ascorbate deficiency in 3T6 fibroblast cultures. The distribution of collagen is moderately affected, more being found in the growth medium, and less in the cell layer, in deficient cultures. While hydroxylation of proline is severely reduced in deficient cultures, in both cell layer and growth medium collagen, the hydroxylation of lysine is only slightly reduced, and the level of free (non-glycosylated) hydroxylysine in collagen is moderately reduced. Hydroxylation of lysine is therefore less sensitive to ascorbate deficiency than hydroxylation of proline, in these cultures, and glycosylation of hydroxylysine is unimpaired by ascorbate deficiency. A greater reduction in hydroxylation of both proline and lysine is observed in collagen-related material in the growth medium than in that associated with the cell layer.