THE CHEMICAL CONSTITUTION OF 

 THE PROTEINS. 



PART I. 



INTRODUCTION. 



THE proteins, of which we know some forty or fifty natural ones 

 occurring in both animals and plants, are divided, according to 

 their origin, solubility, coagulability on heating and other physical 

 characteristics, into the following groups : 



I. Protamines, e.g., salmine, sturine, clupeine, scombrine, cyclop- 



terine, cyprinine. 



II. Histones, e.g., thymus histone, Lota histone, Gadus histone, 

 histone from blood corpuscles. 



III. Albumins, e.g., ovalbumin, conalbumin, serum albumin, various 



plant albumins. 



IV. Globulins, e.g., serum globulin, fibrinogen and its derivative 



fibrin, myosinogen and its derivative myosin. Crystalline 

 vegetable globulins : edestin, excelsin. 

 V. Glutelins, e.g., legumin, conglutin, amandin, occurring in plants, 



soluble in very dilute alkali. 

 VI. Gliadins, e.g., wheat-gliadin, hordein, zein, occurring in cereals, 



soluble in 70-80 per cent, alcohol. 



VII. Phosphoproteins, e.g., caseinogen, vitellin, ichthulin. 

 VIII. Scleroproteins, e.g., keratin from hair, horn, feathers, egg- 

 membrane. Collagen, gelatin, elastin. Silk-fibroin, silk- 

 gelatin. 

 IX. Conjugated Proteins : 



(a) Nucleoproteins : nucleic acid in combination with protein, 



generally L, II., III. 



(b) Chromoproteins : chromogenic substance in combination 



with protein, e.g., haemoglobin. 



(c) Glucoproteins : carbohydrate in combination with protein, 



e.g., mucin, ovomucoid. 



PT. I. I 



