42 ESSENTIALS OF CHEMICAL PHYSIOLOGY 



Salmine (from the salmon roe) and clupeine (from the herring roe) 

 appear to be identical, and have the empirical formula C 30 H 57 N 17 O, J : 

 its principal decomposition products are arginine, amino- valeric acid, 

 and a small quantity of an unknown residue. Sturine (from the 

 sturgeon) yields the same products with lysine and histidine in 

 addition. With one exception, the protamines yield .no aromatic 

 amino-acids, of which tyrosine is a familiar instance ; the exception 

 is cyclopterine (from Cyclopterus lumpus] ; this substance is thus an 

 important chemical link between the other protamines, and the more 

 complex members of the protein family. 



2. The Histories 



These are substances which have been separated from blood 

 corpuscles ; globin, the protein constituent of haemoglobin, is a well- 

 marked instance. They yield a larger number of amino-compounds 

 than do the protamines. They are coagulable by heat, soluble in 

 dilute acids, and precipitable from such solutions by ammonia. The 

 precipitability by ammonia is a property possessed by no other 

 protein group. 



3. The Albumins 



These are typical proteins, and yield the majority of the cleavage 

 products enumerated on pp. 31-35. 



They enter into colloidal solution in water in dilute saline solutions, 

 and in saturated solutions of sodium chloride and magnesium 

 sulphate. They are, however, precipitated by saturating their 

 solutions with ammonium sulphate. Their solutions are coagulated 

 by heat usually at 70-73 C. Serum albumin, egg-albumin, and 

 lact-albumin are instances. 



4. The Globulins 



The globulins give the same general tests as the albumins : they 

 are coagulated by heat, but differ from the albumins mainly in their 

 solubilities. This difference in solubility may be stated in tabular form 

 as follows : 



