Antibodies to Chick‐Tendon Procollagen

Antisera were prepared by immunizing a rabbit with procollagen synthesized and secreted by cells from chick embryo tendons. Specific antibodies were then purified from the antisera by using an immunoadsorbent which contained the isolated NH 2 ‐terminal extensions of procollagen. The purified antibodies were shown to react specifically with intact procollagen as well as with procollagen in which the interchain disulfide bonds were ruptured by reduction under non‐denaturing conditions. The antibodies also reacted with the pro‐α1 chain but not the pro‐α2 chain isolated from the procollagen. There was no reaction after the intrachain bonds in the pro‐α chains of the procollagen were reduced under denaturing conditions and alkylated. In the course of characterizing the antibodies it was shown that the NH 2 ‐terminal extensions on the two pro‐α1 chains and the one pro‐α2 chain of type I procollagen are non‐identical. Also, it was shown that the serum of chick embryos contains an antigen which reacts with the specific antibodies to procollagen.