Hypoxanthine, a Growth Substance for Phycomyces

Abstract

A growth-promoting substance for Phycomyces derived from potatoes was called factor Z1. With further tests it was identified as hypoxanthine in potatoes, though in other materials it may be guanine or a mixture of the 2. Very small quantities of hypoxanthine are effective; it is suggested that it may function in an enzyme system as thiamine, riboflavin, etc., are known to function. The factor is much more effective in the presence of a 2d unidentified substance, factor Z2, than when used alone.