i LIVING MATTEE 23 



Physiological Societies of Great Britain adopted the following 

 scheme of classification in 1907 1 : 



I. Protamines, e.g. salmine, sturine. 

 II. Histories, e.g. thymus histone. 



III. Albumins, e.g. ovalbumin, serum albumin, various vegetable albumins. 

 IV. Globulins, e.g. serum globulin, fibrinogen and fibrin, myosinogen and 



myosin. Vegetable globulins. 

 V. Glutelins, e.g. wheat glutelin) 



VI. Gliadins, *./ wheat gliadin /Present only in cereals. 

 VII. Phosplioproteins, 2 e.g. caseinogen, vitellin, ichthulin. 

 VIII. Scleroproteins, 3 e.g. collagen and gelatin, keratin, elastin, fibroin, 



spongin, amyloid, albumoid, pigments. 



IX. Conjugated proteins. These are combinations of protein with other 

 compounds. 



(a) Nucleoproteins. 

 (6) Chromoproteins, e.g. haemoglobin. 

 (c) Glucoproteins. 



X. Derivatives of proteins. These are formed from members of the other 

 groups by the action of acids and alkalies, or enzymes. 



() Metaproteinj^f^n. 



(6) Proteoses : album ose, globulose, caseose, gelatose, etc. 



(c) Peptones, e.g. fibrin peptone, caseo-peptone, etc. 



(d) Polypeptides, e.g. glycyl-1-tyrosine, d-alanyl-glycine, 1-leucyl- 



d-glutamic acid, d-alanyl-1-leucine, etc. The majority are 

 synthetical compounds. Several have now been isolated 

 from proteins. 



Albumins are coagulable proteins, soluble in distilled water, in 

 dilute salt solutions, in acids and bases, and they are not precipi- 

 tated by saturating the solutions with neutral sodium chloride or 

 magnesium sulphate when the solution 'is neutral, but they are 

 precipitated by these salts when the solution is acid. They are 

 precipitated by saturating the solution with ammonium sulphate. 



Globulins are coagulable proteins, insoluble in distilled water 

 and dilute acids, soluble on the other hand in solutions of neutral 

 salts and dilute bases. They are precipitated on saturation with 

 magnesium sulphate and to a certain extent with sodium chloride ; 

 with ammonium sulphate they are precipitated at a lower degree 

 of concentration ( = J saturation) than that required to precipitate 

 albumin. 



The vegetable globulins differ in many respects from the animal 

 globulins ; they have a great tendency to crystallise, and 'have 

 been prepared in large quantities in a crystalline form (Osborne). 



Fibrinogen and myosin will be discussed in the chapters on 

 Blood Plasma and Muscle. 



Phosphoproteins are characterised by the fact that phosphorus 

 enters into their composition, so that formerly they were erroneously 

 classed with the nucleoproteins. They are distinct from these 



1 Substituted by translator for 0. Cohnheim's (1904) scheme. 



2 Formerly nucleoalbumins. " 3 Formerly albuminoids. 



