Properties and Partial Purification of the Sperm Attractant of Tubularia

The investigations leading to an explanation of the mechanismof sperm chemotaxis in the hydrozoa depend heavily on purificationand identification of the compounds responsible for the attraction.The substance (s) are of low molecular weight, are stable toheat and to high and low pH under moderate conditions, and arehighly positively charged. Recent work using the attractantfrom Tubularia indicates that ion-exchange chromatography coupledwith the proper gradient elution techniques is beginning toyield partially purified attractant. The biological activityis eliminated after strong-acid hydrolysis and after treatmentwith crude proteolytic enzymes, like pronase and pancreatin.The active components of these mixtures of enzymes are neutralproteases with a serine residue in the active site. The stabilityof the molecule (s) to pH, their apparent ninhydrin-insensitivity,and their chromatographic behavior are indicative of a low molecular-weightpeptide, possibly one of the cyclic peptides. Promising avenuesleading to further purification have been opened up by the workreported here, and it would appear to be only a matter of timebefore pure attractant is available for chemical analysis.