THE CHEMISTRY OF THE PROTEINS 93 



was thus proved to be a-amino-/3-oxypropionic acid, the isomeric 



compound, isoserine, being /3-amino-a-oxypropionic acid. 



Leuchs and Geiger have since found a better method for the 



synthesis of serine, from chloracetal, which is best described by 



the following formulae : 



dil 

 / OC.H 5 NaOC,H s /OC,H 5 H 2 S0 4 



C1.CH,.CH< -> C,H 6 O.CH,.CH< -> 



\ OC,H 5 X OC,H, 



HCN + 

 NH 3 

 C J H 5 .O.CH,.CHO -> 



HO conc.HBr. 



C,H 5 .O.CH,.CH(NH a ).CN _> C,H 5 OCH 3 . CH(NH 2 ) . COOH -> 



HO . CH 2 . CH(NH 2 ) . COOH 



By the same method Fischer and Leuchs have prepared a-amino- 

 7-oxyvalerianic acid, a compound which behaves like the other 

 7-oxy acids in easily forming an anhydride or 7-lactone giving 

 the base 



CH 3 . CH - CH 2 . CH(NH 2 ) . CO 

 O 



This substance readily polymerises to a diketopiperazine, a 

 condensation made much use of in the synthesis of proteins. 



Like the oxyaldehydes, the carbohydrates combine with 

 hydrogen cyanide and ammonia ; thus, ^-arabinose gives 

 d-glucosaminic acid, which is identical with the product obtained 

 by the oxidation of glucosamine. Fischer and Leuchs were by 

 this means able to determine the constitution of this important 

 compound. 



The oxyamino acids, according to Fischer, are of extreme 

 importance on account of their relationship on the one hand to 

 the carbohydrates and on the other hand to the proteins, in 

 which they probably occur to a much larger extent than is at 

 present known. 



Another oxyamino acid, S-oxy-a-aminovalerianic acid, has 

 been synthesised by Sorensen, by a method similar to that 

 employed by Fischer in the synthesis of the diamino acids. It 

 is isomeric with Fischer's a-amino-7-oxyvalerianic acid, and 

 constitutes another member of the series of the oxyamino acids. 

 Compared with the monoamino acids the diamino acids are 

 much more difficult to obtain synthetically. The only diamino 



