178 The Biochemistry of Semen 



directly from the epididymis, in which unlike in the seminal vesicle, 

 ergothioneine is absent. The epididymal spermatozoa were diluted 

 with Ringer-phosphate-fructose, and the suspension divided in 

 three equal portions; in one, serving as a control, fructolysis was 

 measured directly, in another the reaction was allowed to proceed 

 in the presence of lO^^^.iodosobenzoate, and in the third after the 

 addition of the same amount of inhibitor, but together with ergo- 

 thioneine, the latter in a concentration of the same order of magni- 

 tude as actually found in vivo in the boar vesicular secretion. It 

 can be seen from Fig. 16, that whereas the presence of iodoso- 

 benzoate alone checked the process of fructolysis, the inhibition was 

 prevented by the simultaneous addition of ergothioneine so that 

 in effect, the spermatozoa were able to proceed with the normal 

 utilization of fructose. 



Biogenesis of ergothioneine 



The mechanism of ergothioneine formation in the boar was 

 studied by pursuing the fate of certain orally administered com- 

 pounds labelled with radioactive sulphur, 253 (Heath, Rimington, 

 Glover, Mann and Leone, 1953). It was found that inorganic sul- 

 phate or thiolhistidine failed to provide a source of sulphur for 

 ergothioneine in the boar; in this respect, the behaviour of thiol- 

 histidine is of particular interest, since it demonstrates again that 

 physiologically occurring substances need not necessarily arise from 

 compounds to which they bear a close, though purely structural, 

 chemical resemblance. Methionine, the amino acid pivotal in bio- 

 logical transmethylations, was capable of supplying the sulphur for 

 the biosynthesis of seminal ergothioneine. The spermatozoa them- 

 selves also incorporated sulphur from labelled methionine but here, 

 the maximum radioactivity appeared several weeks later than in 

 the seminal plasma; this time-lag is presumably due to the fact that 

 the processes of spermatogenesis, sperm maturation, and transport 

 through the epididymis, require substantially more time than is 

 needed for the formation and secretion of seminal plasma in the 

 accessory organs. By administering to a living animal a labelled 

 compound like methionine one might be actually able to deter- 

 mine the time interval required for the processes of sperm formation 

 and transport in the male reproductive organs. When synthetic 



