BIOCHEMICALLY IMPORTANT COMPOUNDS 215 



densation of polyglycine with various aldehydes analogous to 

 that which occurs with the CH2 groups of diketopiperazines : 



J — CONH — CH2 — CO — 

 + R— CHO 



i 



— CONH — CH — CO > — CONH — CH CO — 



I I 



HCOH CHgR 



. I \ ^ 



— CONH C — CO — 



II 

 CH 



As well as aldehydes, unsaturated hydrocarbons can also 

 combine with the polyglycine chain : 



— CONH — CH2 — CO — • 



+ + + CH3 



CH3 — CH=CH2 CH3 — CH=CH CHg \c=CH2 



I i CH3/ j 



— CONH — CH — CO CONH— CH — CO CONH — CH — CO — 



I I I 



CH CH CHg 



/\ /I I 



CH3 CH3 CH3 CH2 — CH3 CH 



CH3 Grig 



valine isoleucine leucine 



Akabori confirmed his hypothesis by direct experiments 

 which he carried out jointly with Hakabushi and Okawa. In 

 the first of these experiments, in which kaolin or ai.o.j were 

 used at a temperature of 110° C, there occurred the poly- 

 merisation of CH2 : NCH2.CN or H2NCH2.CN. In this experiment 

 there was formed after five hours a product giving the biuret 

 reaction. Paper chromatography showed that it contained 

 glycine and polypeptides of glycine. In the second experi- 

 ment polyglycine adsorbed on kaolin reacted at a temperature 

 of 60-80° C with HCHO and CH3CH0. It was shown that this 



