Preparation and use of α-maltosyl fluoride as a substrate by beta amylase

Dorothy S. Genghof, Curtis F. Brewer, Edward J. Hehre

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Abstract

The preparation of pure (amorphous) α-maltosyl fluoride is described. A modification of the procedure of Brauns was used to obtain analytically pure, crystalline hepta-O-acetyl-α-maltosyl fluoride, the structure of which was assigned by19F-and1H-n.m.r. spectroscopy. α-Maltosyl fluoride was obtained by deacetylating the heptaacetate. It behaved as a single compound on thin-layer and paper chromatography, and was essentially completely hydrolyzed to maltose and hydrogen fluoride by 0.01M sulfuric acid in 10 min at 100°. Crystalline beta amylase, likewise, catalyzed essentially complete hydrolysis of α-maltosyl fluoride to give maltose and hydrogen fluoride. The rates of hydrolysis catalyzed by beta amylase preparations from sweet potatoes and soybeans acting on a range of concentrations of the substrate produced linear curves for the relationship, 1/v vs 1/S; reaction constants for crystalline, sweet-potato enzyme were Km 3.6 mM and Vmax ~ 2 μ mol/min/mg. The finding that α-maltosyl fluoride is hydrolyzed 30-60 times faster than maltotriose demonstrates for the first time that beta amylase is capable of effecting hydrolysis at an appreciable rate of a substrate having only two d-glucose residues.

Original languageEnglish (US)
Pages (from-to)291-299
Number of pages9
JournalCarbohydrate Research
Volume61
Issue number1
DOIs
Publication statusPublished - Mar 1978

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ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Organic Chemistry

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