16 



Scientific Proceedings (109). 



acid common to the ones furnishing active hydrolysates and 

 lacking in the others. Acid hydrolysates of yeast and of salmon 

 sperm were also inactive, showing that none of the constituents 

 of nucleic acid were concerned. 



A separation of the amino acids from a casein hydrolysate 

 was therefore undertaken, first into groups by the butyl alcohol 

 extraction method of Dakin. By this method, the monoamino 

 acids are extracted almost quantitatively, and crystallize out 

 of the alcohol as a yellow, granular material, easily filtered out and 

 dried. The proline remains dissolved by the alcohol, while the 

 hexone bases and the dibasic acids remain dissolved in the aqueous 

 phase, unextracted by the alcohol. The active material passed 

 over almost quantitatively with the monoamino acids. 



Various methods of separating this mixture of monoamino 

 acids have been tried. The only reagent so far obtained which 

 precipitates the active material from the mixture of monoamino 

 acids is mercuric sulphate in sulphuric acid solution. This 

 reagent precipitates the following known amino acids: tryptophane, 

 tyrosine, cystine and histidine. Pure preparations of all four 

 of these amino acids have been tested with charcoal treated 

 infusion and found negative. 



For further separation of the compounds precipitated with 

 mercuric sulphate, considerable quantities of casein had to be 

 used, and the preliminary extraction of the monoamino fraction 

 by Dakin's method was to be avoided if possible. It was found 

 that mercuric sulphate precipitated the active material from the 

 original hydrolysate, and further, that it was not even necessary 

 to remove the sulphuric acid with baryta, but that one could neut- 

 ralize the excess acid with crude sodium hydroxide. After 

 filtering off the melanin thus precipitated, the active material 

 could be thrown down by the addition of mercuric sulphate 

 dissolved in 5 per cent, sulphuric acid. Up to this point the separ- 

 ation has been made repeatedly. After removing the Hg from 

 the precipitate by H 2 S, the activity of the preparation varies, 

 probably with the amount of HgSC>4 used, and the concentration 

 of H2SO4 in the mixture. The optimum conditions for precipi- 

 tation have not yet been exactly determined. 



Further purification of the precipitate, freed from mercury, 



