ARTICLES 409 



They conclude that temperature inactivation of natural 

 enzymes was probably due to a degradation of the dispersed 

 phase. 



Surface Action. — It has been shown above that the action 

 of enzymes is related to surface : enzyme action depends rather 

 — to a large extent, if not entirely — on surface. One of the most 

 striking discoveries made recently regarding enzymes is that 

 of Bourquelot and Bridel (191 3), who showed that emulsin 

 could either hydrolyse or synthetise in 90 per cent, alcohol in 

 which it was quite insoluble. Subsequently Bayliss (191 5) 

 extended the discovery to invertase, lactase, urease, catalase of 

 blood, trypsin and pepsin ; while Jacoby (191 6) prepared from 

 the soya bean, by extraction with absolute alcohol and evapora- 

 tion, an active urease powder which was insoluble in water. 

 Similarly Nelson and Griffin (1916), working in America, showed 

 that invertase adsorbed by charcoal or aluminium hydroxide 

 acted quite as well as the same amount in solution. 



It is almost impossible to review the work done recently 

 on surface action without mention of the theory of Faraday 

 that inorganic catalytic action depends on the existence of a 

 clean surface and that impurities which " spoil " the surface 

 hinder catalytic action. In support of this theory Bancroft 

 (191 7) observed that in gas reactions the surface of the catalyst 

 could easily be made inactive by the presence of foreign gases 

 which were strongly adsorbed ; and later (19 18) he pointed 

 out that the products of the action catalysed might themselves 

 accumulate on the surface of the catalyst and appear to bring 

 the reaction to an end, or at least to very much retard it. Such 

 an action may be considered a dispossession from surface, and 

 it is obvious that this may readily lead to erroneous conclusions 

 by causing a reaction to appear complete when it really is not. 

 Proof of the occurrence of such dispossession from surface was 

 given by Bayliss (191 8), who showed that the hydrolysis of urea 

 by urease adsorbed in charcoal could be retarded by saponin, 

 which displaced the urease in the charcoal. The fact that the urea 

 was finally hydrolysed showed that the enzyme had not been 

 destroyed by the saponin. This gives support to the work of 

 Meyerhoff (1914), who, working with the invertase of yeast, found 

 that the inhibitory effect of a series of alcohols and methanes 

 was exactly proportional in homologous series to their power of 

 lowering surface tension. It may be added that Bayliss found 

 that not only did the saponin replace the urease in the charcoal, 

 but that relatively more saponin was adsorbed at a low tem- 

 perature, and that the rate of the reaction varied with the 

 temperature. Working on the urease of the soya bean, Ondera 

 (191 5) showed that amyl alcohol retarded action in high con- 

 centration, and gave further weight to the work of Meyerhoff ; 



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