BY MEANS OF CATALYSTS. CHEIGHTON. 



play the part of a catalyst, was first suggested by van't II off 1 . 

 This was an important suggestion for, in the plant and animal 

 organisims, asymmetric bodies are being built continually from 

 symmetric substances, the synthesis probably being brought 

 about l)y the actions of enzymes or other catalysts. 



It is well known that different substances are only acted 

 on by particular enzymes, it being supposed that the enzyme 

 associates itself with a particular molecular grouping of the 

 substrate. This ''specificity" of the enzymes is \vell seen in 

 the action of various yeasts on disacchrides, an investigation 

 carried out by E. Fischei^, and one which led him to formulate 

 his simile of the "lock and key" relationship. As this implies 

 a close relationship between enzyme and substrate, such as is 

 found in optically active opposites, it has been suggested that 

 enzymes themselves are optically active bodies. Dal'in',? 1 

 investigation on the hydrolysis of optically active esters by the 

 lipase of the liver affords support to this suggestion. He 

 found that when an optically inactive mixture of the t\vo 

 esters of mandelic acid was acted on by lipase, the dextro 

 component hydrolysed more rapidly than the laevo component ; 

 and further, that if the hydrolysis were incomplete, the 

 residual mixture w r as laevo rotatary. The unequal rates of 

 reaction of the two components can only be explained // the 

 enzyme is assumed to be optically active. The work of Fischer 

 and Ahflcrlifi/dcn 4 on the relation of trypsin to the polypeptides, 

 shows that trypsin, too, exhibits a marked affinity for certain 

 optically active groups. 



Attention was first called to the marked similiarity between 

 enzymes and inorganic catalysts by BerzeliusF* . in 1837. He 

 pointed out that: "We have reasons, well founded on fact, to 

 ir.ake the assertion, that in living plants and animals there take 



1 van't Hoff, J. H.: "Die Lagerung- der Atome im Raum." 



2 Fischer. E.: Ber. d. deutsch. chem. Ges., 27, 29 and 92, (1894). 



3. Dakin H D. : Journ. of Physiol.. 30, 253. (1904). 



4. Fischer. E.. and Abderhalden. E.: Zeit. f. physiol. Chem.. 46, 52, 

 (1905) 



5. Berzelius, J. J.: Lehrb. d. Chem.. 3. Aufl., 20-25 (1837). 



