100 CHEMICAL EQUILIBRIA 



Chemists have succeeded in producing esters, 

 such as ethyl butyrate, glyceryl butyrate, glyceryl 

 triacetate, and fats from their alcohols and acids 

 in presence of lipases from pancreatic juice or 

 castor beans. Even glucosides, such as amygdalin, 

 and carbohydrates, e.g. amylose, have been syn- 

 thesised in an analogous manner. Perhaps the 

 most interesting case is the synthesis of proteins. 

 Danilewski and his pupils precipitated so-called 

 plasteins from concentrated solutions of peptones or 

 albumoses, to which rennet or pepsin had been 

 added. The plasteins exhibit the reactions of 

 proteins, but contain less nitrogen. 



A. E. Taylor hydrolysed protamine sulphate by 

 means of trypsin, and after having separated the 

 products, he synthesised them again with the aid 

 of trypsin. In such cases it is not certain that the 

 original substance is restored, e.g. such is not the 

 case in the plastein formation from the products of 

 casein. But in one very important case this has 

 succeeded, namely, with the paranuclein which was 

 prepared by T. B. Robertson by the action of 

 pepsin on the hydrolytic products of casein. The 

 hydrolytic products into which paranuclein may be 

 split up do not bind the antibody which F. P. Gay 

 and Robertson obtained by injection of paranuclein 

 or casein into guinea-pigs. But if these hydrolytic 

 products were synthesised by pepsin the product 

 bound anti-paranuclein, i.e. it was paranuclein. In 

 other words, the authors used the strict specificity 

 of the antibody to discover the presence of its 



