216 CHEMISTRY OF THE PROTEIDS CHAP. 



and phenyl-glycocoll form with calcium-hydroxide and C0 2 have shown 

 that these amino-acids must contain the radical 



,H /H 



H R N/ CH N< 



R N 



/J-JL "\ 2 



V 



^coo 



coo, 



COOH 

 COOH COO Ca COO Ca 



Carbamino-acid radical, Limesalt of same, Calcium carbamino-acetate or 



calcium glycocoll-carbonate, 



that is, the normal lime-salts of the hitherto unknown dibasic carb- 

 amino-acids of the glycocoll series. These compounds are therefore 

 formed by the amphoteric amino-acids, simply adding C0 2 , which 

 thereby becomes de-ionised. 



Quite analogous to the amino-acids behave the peptones, crystalline 

 serum-albumin and dialysed horse-serum. Siegfried points out that 

 the union of CO 2 in the blood appears in a new light, especially in 

 connection with the hypothesis of Setschenow as to conversion of 

 serum albumin into carbo-albumin by the action of C0 2 , and also in 

 connection with the carbo-hsemoglobin of Bohr. 



Siegfried assumes that during muscular activity, in addition to the 

 view according to which muscle-pro teid first takes up 2 and then 

 decomposes, C0 2 being given off, another view will have also to be 

 considered, namely, that C0 2 is bound temporarily as a carbonate, 

 which then undergoes hydrolysis secondarily and so sets free C0 2 . 

 This temporary binding of C0 2 would facilitate oxidative processes 

 going on in the muscle. 



In connection with chlorophyll, the C0 2 taken up may be converted 

 into a carbamino-group, and therefore in future we have, in addition 

 to the question of how C0 2 becomes reduced, also to keep in mind the 

 question of how carbamino-acids are reduced. 



The double nature of amino-acids, i.e. to act either as acids or as 

 bases, is interfered with as soon as one of the NH 2 or COOH radicals 

 is bound up. Curtius and Gobel 1 have shown that glycin- ester, 

 H 2 N.CH 2 .COOC 2 H 5 , and E. Fischer 2 that other amino- acid -esters 

 are strong bases (as already mentioned in connection with sarcosin 

 and betain, p. 212); Schiff, 3 on the other hand, found methylene- 

 compounds to be acids, as the amino-radical is joined to formaldehyde ; 



1 T. Curtius and F. Gobel, Journ.f. prakt. Ohem. (2) 37. 150 (1888). 



2 E. Fischer, Ber. d. deutsch. diem. Ges. 34. I. 433 (1901). 



3 E. Schiff, LieUgs Ann. 310. 25 (1899), 316. 242 (1901), 319. 59 (1901). 



