PBOTAMINS AND HISTONS. 431 



washed thoroughly, dissolved in sulphuric acid and from the solution 

 the picric acid is removed ydth ether. The protamin sulphate is 

 then thrown down with alcohol and the whole process is repeated if 

 necessary till the substance forms a white flocculent precipitate. 



The protamins are strong bases and the aqueous solution possesses 

 a marked alkaline reaction. With acids they form well defined 

 salts. The sulphates usually form a white powder which, in the 

 case of sturin and accipenserin, is very soluble in water. The sul- 

 phate of clupein is soluble in warm water and separates out on cool- 

 ing as oily globules. The solutions of protamins are levo-rotatory 

 and give the biuret reaction in the cold. Cyclopterin is the only 

 protamin which gives the Millon test thus indicating the presence of 

 an aromatic group. From it Kossel and Kutscher obtained 8.3 per 

 cent, of tyrosin. Clupein gave amido valerianic acid. In the pres- 

 ence of ammonia they precipitate pepton solutions. It is of inter- 

 est to note that the sulphates are precipitated by saturated salt or 

 ammonium sulphate solutions. The protamins are precipitated by 

 the usual alkaloidal reagents even in neutral or slightly alkaline 

 solutions. In this respect they differ from the peptons and albu- 

 moses which require an acid reaction. Sodium tungstate, phospho- 

 tungstate, chromate, ferrocyanid, picrate and solutions of iodin and 

 bromin give precipitates. Benzoyl chlorid, silver nitrate and mer- 

 curic chlorid likewise precipitate the protamins. They are also 

 thrown down as cuprous compounds by copper sulphate and sodium 

 hyposulphite. 



On boiling with dilute sulphuric acid for a short time the pro- 

 tamins hydrolyze partially, forming substances which may be com- 

 pared to the peptons. To these primary cleavage products Kossel 

 has applied the term proton. On prolonged boiling with acid these 

 are decomposed, giving rise to the hexon bases. Kossel and Mathews 

 have shown that while pepsin is without effect on the protamins, 

 trypsin decomposes them, like an acid, yielding protons and eventu- 

 ally the hexon bases. In this case the biuret reaction disappears as in 

 the auto-digestion of the pancreas. In this respect the digestion of 

 protamins is similar to that of the more complex proteids (see page 

 424). 



Salmin and clupein according to Kossel ' are identical and possess 

 the formula CjgH^NjyOg. The composition of sturin is represented 

 by CjjHjjNjgOj and that of accipenserin by CgsH^N^Oj. 



As to the inner structure of the protamin molecule very little that 

 is definite can be said. The large amount of arginin present in 

 these substances indicates that this base forms an important part of 

 the molecule. The hexon bases contain each 6 carbon atoms and 

 the comparison of these by Kossel to the hexoses of the carbohy- 

 drate group is certainly very ingenious. Usually on hydration the 

 ^Zeits. physiol. Chem., 25,168, 173. 



