Physiologie. 137 



can give rise to two stereoisometric hexosides (e. g. a and ß 

 methylglucoside) differing only in the relative space-relations of 

 an atom of H, and the RO. group, attached to the carbon 

 atom; these however require diiferent enzymes for their hydro- 

 lysis. Yet it would seem that the enzyme is only out of har- 

 mony with the glucoside at its terminal point in as much as 

 the action of emiilsin on milk-sugar is hindered not only by 

 glucose but also, though to a iess extent, by «-methyl glucoside 

 which is not attacked by emulsin /!?-methyl glucoside being 

 readiiy hydrolysed. Glucose and galactose are the only hexoses 

 affording glucosidic derivatives fermentable by sucroclastic en- 

 zymes. Hydrolysis is inhibited by the slightest change in confi- 

 guration other than that involved in the passage from glucoside to 

 galactoside or by any shortening of the chain of C-atoms. Thus, 

 apparently the enzyme and the hydrolyte must be in complete 

 correlation. Galactose differs from glucose merely in having the 

 radicles attached to the fourth C-atom in reversed order. As 

 galactose and galactosides are fermented Iess readiiy than 

 glucose and glucosides the change in configuration although 

 sufficient to retard the action is not sufficient to prevent it. 



Fructose has as inhibiting action except on invertase. This 

 is probably accounted for by the difference in configuration 

 Seen on comparing its 7-oxide formula: 



OH H H 



HO . H2C— C— C— C— C— CH2 . OH 



H ÖH/ 







with that of glucose given above. E. Drabble (London). 



Armstrong, E. F., Studiesonenzym action. V. Hydro- 

 lysis of Isomeric Glucosides and Galactosides 

 by Acids and Enzymes. (Proc. Royal Soc. London. 

 Nov. 1, 1904. 



Bourquelot and Herissey hold that the action of 

 Emulsin on Milk sugar is due to the presence of small quan- 

 tities of lactose; against this the following facts are cited. A 

 linear expression such as should then mark the early stages 

 is not found. The action of emulsin on milk sugar is most 

 strongly retarded by glucose and only to a slight extent by 

 galactose, whereas galactose alone effects the action of lactose. 

 The curves for emulsin-action fall off more rapidly than those 

 for lactose showing that the action of the products in remo- 

 ving the enzyme is greater in the former case. 



It would appear that emulsin can act on /j-galactosides as 

 well as on /?-glucosides. 



The different hexosides vary widely in stability. When 



