Chromatographic isolation of thymic factors impairing neuromuscular transmission.

Thymopoietins I and II are chemically related peptides able to inhibit neuromuscular transmission. They were first isolated from bovine thymus by a protein-denaturating method, which may have destroyed other thymic factors displaying the same biological activity. The present investigation, based on a new gentle isolation procedure, suggests that thymopoietins are the only factors impairing neuromuscular transmission that are present in the thymus. The yield of the new procedure is at least twice as high as that of the original method.