PHYSIOLOGICAL CHEMISTRY 305 



(1) Protamines. (2) Histones. 



(3) Albumins. (4) Globulins. 



(5) Phospho-proteins. (6) Sclero-protems. 

 (7) Compound proteins. 



The Protamines. These substances are the simplest proteins 

 known (Kossel). They occur combined with nucleic acid in the sper- 

 matozoa of certain fishes, such as the salmon, sturgeon, mackerel and 

 herring. Sturin from the sturgeon has the formula C 36 H 6S N 19 7 ; 

 salmin (salmon) and dupein (herring) have the formula C 30 H 57 N 17 6 . 

 They are difficult to obtain in a state of purity, and the technique is 

 complicated. Upon hydrolysis they yield large amounts of the hexone 

 bases arginin, lysin, histidin, especially arginin. 



Monamino acids are combined into the protamines, but only one 

 cyclopterin has so far yielded a ringed amino acid grouping. 



The protein nature of the protamines is shown by the fact that they 

 yield the Biuret test. 



The Histones occur mainly in combination. Perhaps the best known 

 example is the globin portion of haemoglobin. They also occur com- 

 bined in the nuclei of blood corpuscles, e.g. in the red corpuscles of the 

 goose and in the white corpuscles of the thymus gland. 



The histones are somewhat more complicated than the protamines. 

 Bang gives the following characteristic reactions : 



(a) They are precipitated from watery solution by ammonia the 



precipitate being soluble in excess. 



(b) In presence of salts they are coagulable by hea't. 



(c) They give a precipitate with nitric acid in the cold, soluble on 



heating, reappearing on cooling (cf. Proteoses and Peptones). 



THE ALBUMINS AND GLOBULINS. 



These two groups have been already studied in the preceding experi- 

 ments with the egg-white solution. The main difference between the 

 albumins and the globulins is that of solubility. It has also been 

 shown chemically that the products of hydrolysis differ, the albumins 

 yielding no glycin. Upon hydrolysis all yield members of the chief 

 amino acid groups (see table, p. 299). 



Albumins are soluble in distilled water and in saturated solutions of 

 all neutral salts except ammonium sulphate and anhydrous sodium 

 sulphate, in which they are insoluble. They are, however, soluble in 

 half-saturated solutions of these salts (see table, p. 312). 



Globulins are insoluble in distilled water and in saturated solutions 

 of all neutral salts. They are, moreover, insoluble in half-saturated 



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