88 PHYSIOLOGICAL CHEMISTRY. 



(c) Coagulated Proteins. Insoluble products which result 

 from (i) the action of heat, on their solutions, or (2) the action of 

 alcohol on the protein. 



2. SECONDARY PROTEIN DERIVATIVES. 1 



Products of the further hydrolytic cleavage of the protein 

 molecule. 



(a) Proteases. Soluble in water, non-coagulable by heat, and 

 precipitated by saturating their solutions with ammonium or zinc 

 sulphate, 2 e. g., protoproteose, deuteroproteose. 



(b) Peptones. Soluble in water, non-coagulable by heat, but 

 not precipitated by saturating their solutions with ammonium sul- 

 phate, 3 e. g., antipeptone, amphopeptone. 



(c*) Pep tides. Definitely characterized combinations of two or 

 more amino acids, the carboxyl group of one being united with the 

 amino group of the other with the elimination of a molecule of 

 water, 4 e. g. f dipeptides, tripeptides, tetrapeptides, pentapeptides. 



CLASSIFICATION OF PROTEINS ADOPTED BY 

 THE BRITISH MEDICAL ASSOCIATION. 



I. SIMPLE PROTEINS. 



1. Protamines, e. g., salmine, clupeine. 



2. Histones, e. g. } globin, scombrone. 



3. Albumins, e. g., ovalbumin, serum albumin, vegetable albu- 

 mins. 



4. Globulins, e. g., serum globulin, ovoglobulin, vegetable glob- 

 ulins. 



5. Glutelins, e. g. } glutenin. 



6. Alcohol-soluble proteins, e. g., zein, gliadin. 



7. Scleroproteins, e. g. } elastin, keratin. 



8. Phosphopro terns, e. g., caseinogen, vitellin. 



x The term secondary hydrolytic derivatives is used because the formation of 

 the primary derivatives usually precedes the formation of these secondary 

 derivatives. 



2 As thus defined, this term does not strictly cover all the protein derivatives 

 commonly called proteoses, e. g., heteroproteose and dysproteose. 



8 In this group the kyrkies may be included. For the present it is believed that 

 it will be helpful to retain this term as defined, reserving the expression peptide 

 for the simpler compounds of definite structure, such as dipeptides, etc. 



* The peptones are undoubtedly peptides or mixtures of peptides, the latter 

 term being at present used to designate those of definite structure. 



