Serum gonadotrophin

Abstract

The method is economical and is suitable for large-scale operation and depends firstly upon precipitation of inert serum proteins by metaphosphoric acid. Very little loss in gonadotrophic activity occurs at this stage. The active principle is then adsorbed upon benzoic acid and by soln. of the latter in acetone a stable initial powder is obtained averaging 27 I.U./mg. and accounting for 79% of the activity (data compiled from 39 individual preparations totalling 48 I. of serum). The initial powder is further fractionated by means of titration in 50% alc. to pH 4.8; an insoluble portion representing 92% by wt. and practically devoid of activity is rejected, while from the soln. the active fraction is recovered by further addition of alc. This material contains 150-600 I.U./mg. and is readily soluble in water. The avg. yield at this stage is 92%, making an overall yield of 73% of activity from the original serum. The active material contains 2.5-3.5% of hexose (orcinol method), while the inert fraction insoluble in 50% alc. at pH 4.8 contains 7.5-8.5% of hexose.