132 CHEMISTRY OF THE PROTEIDS CHAP. 



t 

 of dilute, cold alkalies does away with the objection hitherto raised 



against the occurrence of diacipiperazin compounds in the albumin 

 molecule. It used to be argued, as no diacipiperazin compounds were 

 obtainable after digesting albumins by means of ferments acting in 

 dilute alkaline solutions, that such ring compounds could not be 

 present, but Fischer points out that diacipiperazin-rings are readily 

 formed during the synthesis of polypeptids, and says : "I hold it for 

 probable that they are also present in some of the proteid compounds. 

 They probably play a part during the denaturalisation of native 

 albumins, and also during the formation of alkali-albuminates." 



LIST OF THE POLYPEPTIDS AND SOME OF THEIR DERIVATIVES 

 BUILT UP BY E. FISCHER'S SCHOOL 



The figures I. to IX. refer to the consecutive papers published by 

 Emil Fisher and his school. See footnotes on pp. 125-126. 



Glycyl-glycin-Derivatives (I.) 



Glycyl-glycin : NH 2 . CH 2 . CO . NH . CH 2 . CO . OH. 



Glycyl-glycin-ester : NH 2 . CH 2 . CO . NH . CH 2 . CO . OC 2 H 5 . 

 Glycyl-glycin phenyl-cyanate : 



C 6 H 5 . NH . CO . NH . CH 2 . CO . NH . CH 2 . COOH. 

 Carbethoxyl-glycyl-glycin-ester : 



C 2 H 5 . OC . NH . CH 2 . CO . NH . CH 2 . CO . OC 2 H 5 . 

 Carbamino-glycyl-glycin-ester : 



NH 2 . CO . NH . CH 2 . CO . NH . CH 2 CO . OC 2 H 5 (?). 



Di-glycyl-glycin-Derivatives 



Di-glycyl-glycin : NH 2 CH 2 CO . NHCH 2 CO . NHCH 2 CO . OH. 

 a-brom-propionyl-glycyl-glycin : 



CH 3 . CHBr . CO . NHCH 2 CO . NHCH 2 CO . OH. 

 Alanyl-glycyl-glycin : 



CH 3 . CH(NH 2 ) . CO . NHCH 2 CO . NHCH 2 CO . OH. 

 Carbethoxyl-alanyl-glycyl-glycin : 



C 2 H 5 C0 2 . NH . CH(CH 8 ) . CO . NHCH 2 CO . NHCH 2 CO . OH. 

 a-bromiso-capronyl-glycyl-glycin : C 10 H ir 4 N 2 Br. 



