On the Application of Barfoed's Reagent to show the Hydrolysis of Disaccharides by Enzymes.

The methods which are used to, show the hydrolytic splitting of lactose and maltose, are not so simple as those which demonstrate the hydrolysis of saccharose and polysaccharides. The reason for this is that in the latter case there is a change from a non-reducing carbohydrate to a reducing sugar, whilst in the former the original material will already reduce cupric hydrate in alkaline solution. It is, therefore, necessary to make a quantitative estimation of the reducing power in two solutions, one of which is a control containing the boiled enzyme and the other is a similar mixture containing the unboiled enzyme.1 The presence of lactase and maltase can be just as easily proved as the ordinary amyloclastic enzymes, by using copper acetate in acetic solution.2 This reagent is reduced by monosaccharides, whilst under proper conditions, disaccharides leave it unchanged. Hinkel and Sherman have recently investigated this reaction by comparing the behaviour of the reagent with glucose, maltose, lactose and saccharose.3 They found that using five cubic centimetres of the reagent the presence of 0.0004 gramme glucose can be shown, either alone, or mixed with disaccharides, provided that the total weight of disaccharide does not exceed 002 gramme. The period