THE INDIVIDUAL GROUPS OF PROTEINS. 



PROTAMINES. 



The protamines occur in ripe fish sperm in which they are present as 

 salts of nucleic acid. Salmine, the first known member of the group, was 

 discovered by Miescher in salmon sperm. The other members have been 

 isolated by Kossel and his pupils from the sperm of other fishes. They are 

 named according to the fish from which they are obtained, e.g. sturine from 

 sturgeon, clupeine from herring, scombrine from mackerel, cyprinine from 

 carp. Our knowledge of these proteins is almost entirely due to Kossel and his 

 pupils, who have shown that they are composed principally of diamino acids, 

 especially arginine, which in some cases makes up over 80 per cent, of the 

 molecule. It seems that they are the diamino acid constituents of muscle 

 protein since the testicles grow at the expense of the muscles in the spawning 

 season, the fish taking no food and living upon the mono-amino acid 

 portion. 



Preparation. 



The ripe or nearly ripe testicles are smashed up, shaken continuously 

 with water and the liquid strained through a cloth. The milky fluid, which 

 contains the spermatozoa, is acidified with a few drops of acetic acid which 

 causes .them to clot together. The clotted mass is filtered off, \ oiled 

 several times with alcohol and then with ether to remove fats and dried in 

 the air. The dry matter (about 100 gm. portions) is shaken for 15 minutes with 

 5 times its volume of i per cent, sulphuric acid, filtered off and the extraction 

 with acid repeated several times. The combined extracts are treated with 

 3 volumes of alcohol. Protamine sulphate is precipitated, filtered off after 

 12-24 hours, redissolved in water and precipitated with alcohol. It is dis- 

 solved in about 1500 c.c. of hot water ; on cooling, protamine sulphate separates 

 as a yellowish or brownish oil. The solution is concentrated and allowed to 

 stand in a separating funnel. A further quantity of oil, but contaminated with 

 nucleic acid, collects. It is dissolved in warm water and treated with sodium 

 picrate. The precipitate of protamine picrate is filtered off, washed and re- 

 converted into sulphate by extraction with ether in presence of an excess of 

 sulphuric acid. The aqueous acid solution is precipitated with alcohol ; 

 solution in water and precipitation with alcohol is repeated. Solution and 

 precipitation must be repeated until the protamine sulphate forms a loose, white 

 precipitate and is not sticky. 



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