150 Mr. W. Sutherland. [July 26, 



position of egg albumin true within the limits of analytical error, and enable 

 us to write the main part of the egg albumin molecule as 120 (C12H20N3O4). 



The formula of globulin cannot be quite so much simplified, but we can 

 write it 146 (C12H19N3O4) + 14N", neglecting S meanwhile. The group 

 C12H20N3O4, which is repeated 120 times in the albumin molecule, is closely 

 related on the one hand to the polypeptides synthesised by E. Fischer, and to 

 the pure peptones prepared by Siegfried. For the derivation of dipeptides 

 and tripeptides from the amino acids by abstraction of water we have the 

 equations* 



2XH 2 (CH 2 ) w COOH-H 2 = NH 2 (CH 2 ) 2 „NHCOCOOH, dipeptide; 

 3NH 2 (CH 2 ) w COOH-2H 2 = NH 2 (CH 2 ) 3w (NHCO) 2 COOH, tripeptide. 



If, now, in this general formula for a tripeptide we put n = 3, we obtain 

 Ci 2 H23N 3 4 , a group containing 3H more than our typical albumin group 

 above. If, then, we remove 3H from this polypeptide, we obtain a trivalent 

 radicle, C12H20N3O4, which we find repeated 120 times in the molecule of egg 

 albumin. It hardly matters at present how many times CH 2 may be removed 

 from one of these groups and inserted into others, for we are considering only 

 the broad plan on which the albumin molecule is built. 



Similarly, the properties of globulin depend on a certain preponderating 

 group whose average composition is close to Ci 2 Hi 9 N 3 4 . These groups are 

 almost as closely related to the pure natural peptones prepared by Siegfried 

 as to the synthesised polypeptides of E. Fischer, f These are the antipeptones 

 a and /3, or trypsin-fibrin peptones C10H17N3O5 and CHH19N3O5, of which the 

 next homologue would be Ci 2 H 2 iN 3 05, differing from our albumin group by 

 OH and from our globulin group by OH 2 . Even if these formulas need to be 

 doubled, the relation would not be altered. Then come the pepsin-fibrin 

 peptones a and /3, C21H34N6O9, C 2 iH3 6 N 6 Oi . It is significant that the latter 

 could be produced by the additive union of the antipeptones a and ft. 



Now, the experiments of W. Neumann and Siegfried have yielded the 

 result that in the antipeptones the H ions are to the OH ions as 2:1, 

 and in the pepsin peptones as 3 : 2. But the number of H ions gives the 

 number of CO OH radicles in the molecule, while that of the OH ions gives 

 the number of NH 2 radicles. Hence we infer that the group Ci 2 Hi 9 N30 4> 

 when converted into an antipeptone, contains COOH twice and NH 2 once. 

 Hence, in the joining up of such groups to the number of 146 to form 

 globulin, there must be a large amount of internal salt formation, since 

 COOH occurs only two or three times in the complete globulin molecule. It 



* See Cohnheirn's ' Chemie der Eiweisskorper,' p. 59. 



t Siegfried, 'Ber. d. Deutsch. chem. Ges., J vol. 33 ; ' Zeitsch. f. Physiol. Chem.,' vols. 35 

 38, 45. 



