166 The Biochemistry of Semen 



Spermidine 



Dudley, Rosenheim and Starling (1927) also succeeded in the 

 isolation of spermidine, a base present in the mother-liquor after 

 separation of spermine phosphate; spermidine phosphate is much 

 more soluble than spermine phosphate and crystallizes from the 

 25% ethanolic mother-liquor, after the removal of spermine phos- 

 phate, when the concentration of alcohol is increased to 50%. The 

 properties of spermidine are similar to those of spermine. It gives 

 the same pyrrole reaction and behaves in an identical manner 

 towards precipitating reagents including phosphotungstic acid. 

 Spermidine is optically inactive, and yields like spermine, the semen- 

 like odour when a solution of its chloroaurate is treated with 

 magnesium. The structural formula of spermidine, proved by syn- 

 thesis, is that of a-[y'-aminopropylamino]-(5-aminobutane: 



CH2*CH2*CH2*NH'CH2'CH2Cri2'CH2 



I I 



NHa NH2 



Spermidine 



The close chemical relationship of spermine and spermidine 

 suggests that the two bases may be related metabolically. Little, 

 however, is as yet known about the biogenesis and metabolism of 

 either of these two substances. So far as spermine in human semen 

 is concerned, there can be little doubt that its high concentration 

 which is of the order of 50-250 mg./lOO ml., is due chiefly to the 

 prostatic secretion. Fuerbringer showed in 1881 that the prostatic 

 gland contributes by far the greatest part of seminal spermine; on 

 addition of two drops of 1 % solution of (NH4)2HP04 to ten drops 

 of freshly collected prostatic fluid, Fuerbringer observed an almost 

 instantaneous formation of Boettcher's crystals; the examination of 

 secretions of the other accessory organs gave a negative result. The 

 concentration of spermine in the human prostate is subject to varia- 

 tions but exceeds that of any other organ. This follows both from 

 Harrison's findings (1931) as well as from the survey carried out by 

 Hamalainen (1947) who determined spermine as flavianate after pre- 

 cipitation from trichloroacetic acid extracts; the highest values 

 obtained by the Finnish investigator in the different organs (ex- 

 pressed as mg. spermine phosphate per 100 g. tissue, wet weight) 



