TRANSACTIONS OF SECTION B. 57^ 



As the glucosides are obtained in a pure state by tbis method they crystallise 

 Mvithout much difficulty. The /3-deriyatives are specially easy to obtain, whereas 

 •when Fischer's method is used, which involves heating' a mixture of the sugar 

 and alcohol together with a small quantity of cblorhydric acid, the greater part 

 of the product is the n-glucoside ; the methods therefore supplement one another. 

 A series of alkyl derivatives of glucose and of galactose have been investigated. 



Aceto-halogen-derivatives of both maltose and milk sugar have been prepared 

 and the former converted into the corresponding /3-methylmaltoside— the simplest 

 case_ of a trisaccharide. The behaviour of this compound towards enzymes is 

 specially interesting. As Fischer has shown, maltose is an a-glucoside,i but in 

 the synthetic compound the methoxy-group is introduced in the /S-position. 

 Methylmaltoside is, in fact, a double a/S-glucoside similar to the natiu-al gluco- 

 side amygdalin, and resembles this latter in its behaviour with yeast maltase, the 

 maltose part of the molecule being hydrolysed, so that methylglucoside and 

 glucose are formed ; on the other band, when subjected to the action of emulsin, 

 the maltoside is resolved into methyl alcohol and maltose. An exactly analogous 

 behaviour is shown by the corresponding phenolmaltoside. 



Eecently, ^-acetochloro-derivatives of sugars have been prepared by Skraup by 

 the action of phosphorus peutachloride and aluminium chloride on the pentacetyl- 

 derivatives ; but in this case molecular rearrangement takes place, both the'n- 

 and ^-pentacetates giving the same chloro-derivatives. The investigation carried 

 out by the author has shown that the /3-balogen-derivatives are tbe more .stable, 

 and that in presence of alkali the a- are rapidly converted into the /3- derivatives, 

 which is a definite proof that the isomerism" and likewise that of the glucosides 

 is stereochemical. This instability has unfortunately prevented a synthesis of 

 the a-glucosides of the phenols ; and it is of interest to note that nearly all the 

 natural glucosides which have been physiologically tested belong to the /3-series. 



6. The Synthetical Action of Enzymes. 

 By Dr. E. Frankland Armstrong. 



It has long been known that enzymes bave the power of inducing bydrolysis, 

 particularly of disaccharides containing a 'glucoside-linkage,' but the observation 

 of Croft Hill that enzymes can also effect synthetical changes is of quite recent 

 date; his experiments have shown that when maltose is bjdrolysed by maltase, 

 just as in the case of the bydrolysis of esters by acids, a reversible action takes 

 place in concentrated solutions; and that in concentrated solutions of glucose a 

 disaccharide is formed. Some uncertainty exists as to tbe nature of this su"-ar 

 Hill claiming that it is maltose, whereas Emmerling contends that he has identified 

 it by means of the pbenylosazone with isomaltose. Bearing in mind the great 

 difficulty experienced in purifying and characterising the osazoues of disaccbarides, 

 it is impossible, on the strength of this one derivative alone, to decide the ques- 

 tion ; but as Emmerling has sbown that the sugar formed is not fermented by 

 * top yeast,' it may be concluded that it cannot be maltose. 



Croft Hill's conclusion that enzymes exercise .synthetic functions has been 

 justified by the later observations of Kastle and Loevenhart and of Hanriot on 

 lipase, the enzyme by which fats are hydrolysed, the.se observers having shown 

 that this enzyme is capable of producing both esters of fatty acids and glycerides. 

 In these cases stereochemical isomerism is out of the question, and the products are 

 identical with tbe natural substances. Emmerling lias also demonstrated that the 

 synthesis of amygdalin from mandelio-nltrile glucoside and glucose may be effected 

 by means of maltase. 



It is interesting to note that Fischer has proved that isomaltose, not maltose, 13 

 formed by the action of acids on glucose, showing that in their case the action 

 is not strictly analogous to the reversible hydrolysis of esters by acids, and it is, 



' a-glucosides are those hydrolysed by maltase, 0-glucosides those hydrolysed by 

 emulsin. 



P p 2 



