WORK 119 







hyde. Sorensen (379) has shown that the simple amino acids react 

 with formaldehyde with the formation of methylene compounds. 

 Irvine (208) carried out some very interesting work on the nature of 

 the condensation which took place between sugars and amino bases. 

 He has found that, in the case of glucose anilide, the simple alde- 

 hyde condensation did not occur, as was formerly believed. Spiegel 

 (381) suggested that certain polypeptide groups present in the protein 

 molecule were linked together by means of carbon atoms, and he 

 attempted to bring about a synthesis of protein from protein de- 

 composition products and formaldehyde. He stated that he obtained 

 products which suggested that a synthetic change had taken place. 



It is more than probable that it is the union of the nitrogen-con- 

 taining radicles with the reactive aldehyde, or ketone, groups which 

 brings about the protein synthesis in the body. Very reactive alde- 

 hydes and ketones such as methylglyoxal and glyceric aldehyde can 

 certainly be formed in the decomposition of the carbohydrates, and 

 indeed they probably arise during the normal course of carbohydrate 

 catabolism in the organism ; at any rate various products known to 

 arise during the decomposition of carbohydrates in vitro have also 

 been recovered from animal tissues. 



(b} In uiuo Experiments. 



A certain amount of experimental work has been carried out in 

 vivo. Thus, Spiro (382) found that, if glycine and fructose were in- 

 jected into an animal simultaneously, a dicarboxylic acid could be 

 isolated from the urine which was not present when either substance 

 was injected alone. Quite recently Knoop (222) has made an 

 extremely valuable contribution to this question. He found that, 

 after the injection of an a-keto acid, nitrogen could be added on and 

 an a-amino acid formed within the tissues. The synthetized sub- 

 stance was asymmetric. It would thus appear that the first phase of 

 the oxydative breakdown of the amino acid is a reversible process. 

 He also found that a-oxyacids could be converted into a-amino acids. 

 He held that this proved the possibility of the union of the decom- 

 position products of sugar and ammonia to form a protein nucleus. 

 Knoop and Kertess (223) have fully confirmed this previous finding. 

 Embden and Schmitz (118) attacked the problem in another fashion 

 and have contributed valuable confirmatory evidence. These workers 



