THE ATTEMPTED SYNTHESIS OF PROTEIDS. 



At 190 dry glutaminic acid is converted into pyroglutaminic 

 and at a higher temperature this, in turn, is converted into pyrrol. 1 



35 

 acid, 



The attempted synthesis of proteids. Since Wohler in 1828 

 succeeded in making urea artificially from its elements, the strides 

 that organic chemistry has made have been prodigious. Complex 

 substances, previously made only in the living laboratory of plants 

 and animals, are now manufactured daily in the test tubes and retorts 

 of the chemist. The substances of most importance to vital processes, 

 the carbohydrates and the proteids, have been among the last to yield 

 before this advance, but we have seen how sugar has given way to 

 Fischer ; and there are signs that the last conquest of organic chemistry, 

 the synthesis of proteids, cannot be far distant. I propose to sketch one 

 or two of the principal attempts that have been made in the manu- 

 facture of albuminous from simpler substances. 



Scliutzenbergers experiments. We have already seen that the pro- 

 ducts of decomposition of a proteid are extremely numerous, but briefly 

 they fall into two principal groups, the fatty compounds (generally con- 

 taining an amidogen radicle) and the aromatic compounds or derivatives 

 of benzene. To Schiitzenberger 2 belongs the credit of an attempt to 

 build up from some of the compounds he had shown could be obtained 

 from albumin, something like the original proteid. 



In order to effect the synthesis of proteid material, he considered it 

 necessary to combine a molecule of a leucine (i.e. an amido-fatty acid) 

 with a molecule of a leuceine (an amido-acid of the acrylic series), with 

 elimination of water, and then to combine this complex group with one 

 or more molecules of urea and oxamide, also with the elimination of 

 water. We have already seen that the method he had adopted for the 

 breaking up of proteids heating with alkali leads to hydrolysis ; so in 

 any attempt at synthesis he recognised as a sine qua non the necessity 

 of some method of dehydration. 



The provisional formula he gives is the following : 



H 2 C 2 4 +2 NH 3 +3C m H 2m+1 N0 2 +3 C n H 2n _ 1 N0 2 

 with elimination of eight molecules of water. This would give 



the percentage composition calculated from the formula agrees closely 

 with that of albumin. 



1 Bernhoimer, JBer. d. deutscli. chcm. Gesellsch., Berlin, Bd. xv. S. 1222. 



2 Compt. rend. Acad. d. sc., Paris, tome cvi. p. 1407 ; cxii. p. 198. 



