Subunit structure of wheat germ agglutinin

Cells isolated by enzymic digestion of embryonic tendon were incubated under N₂ so that they synthesized and accumulated the unhydroxylated form of procollagen which is known as protocollagen and which is largely comprised of pro-α chains linked by interchain disulfide bonds. The cells were then exposed to O₂ so that the intracellular protocollagen was hydroxylated and secreted as procollagen. When the hydroxylation was allowed to proceed at 31° or 34°, the procollagen secreted into the medium was triple-helical but its hydroxyproline content was less than two-thirds and its hydroxylysine content was less than half the control. Even when the hydroxylation was allowed to occur at 37°, the procollagen secreted by the cells was under-hydroxylated by about 15% in terms of its hydroxyproline content and about 45% in terms of its hydroxylysine content. The results may have consequences for collagen synthesis by tendons and similar tissues $\text{in vivo}$, since temporary anoxia in such tissues may well lead to the synthesis of a less stable procollagen or to fibers of decreased tensile strength.