A one-step ultramicro method for the assay of intestinal disaccharidases

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Abstract

  • 1.

    1. A procedure is described for the assay of maltase, isomaltase, sucrase, lactase, cellobiase, and trehalase activity in homogenates of human small-intestinal mucosa. The disaccharide hydrolysis and the coupled enzyme reactions yielding a colored product occur simultaneously in a single incubation step.

  • 2.

    2. This one-step procedure for disaccharidase activity assay is conveniently veniently used on the ultramicro scale, and the method then utilizes only about 125 of the amount of tissue needed for a previously described two-step method (9). The one-step method is therefore especially suitable for the analysis of pieces of mucosa obtained by peroral capsular biopsy, which usually are small. It is also simpler to perform than the two-step method, which is especially advantageous when large numbers of samples have to be analyzed, as in column chromatography. For enzyme kinetic studies of the disaccharidases, however, the two-step method should be preferred.

  • 3.

    3. Maltase activity, measured with the one-step method, was found to be 40% lower than when measured with the two-step method. This was probably caused mainly by the lower substrate concentration that had to be used because of inhibition of glucose oxidase by maltose. The isomaltase, sucrase, lactase, cellobiase, and trehalase activities were the same, whichever of the two methods was used for the assay.

  • 4.

    4. In the one-step method the substrates used must be free from glucose. A simple method for the preparation of glucose-free disaccharide solutions is described.

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  • Cited by (0)

    1

    Present address: Gastroenterological Research Unit, Royal Children's Hospital Research Foundation, Melbourne, Australia.

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