Fertilization: a uterine glycosaminoglycan stimulates the conversion of sperm proacrosin to acrosin.

Acrosin is a proteinase required for mammalian fertilization, and in freshly ejaculated spermatozoa exists as an inactive zymogen, proacrosin. A factor prsent in uterine flushings of gilts stimulates the conversion of highly pruified boar proacrosin to acrosin. Characterization of this factor indicates that its active component is a glycosaminoglycan.