TY - JOUR
T1 - Preparation and use of α-maltosyl fluoride as a substrate by beta amylase
AU - Genghof, Dorothy S.
AU - Brewer, Curtis F.
AU - Hehre, Edward J.
N1 - Funding Information:
The authors are grateful to Professor F. Micheel (Universitst Miinster) for helpful suggestions concerning the preparation and purification of glycosyl fluorides. We also thank Dr. W. J. WheIan and Dr. J. J. Marshall for the gift of cr-D-glucosidase-free, sweet-potato beta amylase, and Dr. T. Komaki of Nagase and Co. for a sample of soybean beta amyIase. This study was supported by a grant (to E. J. H.) from the Corn Refiners Association, Inc., Washington, D.C., and by Public Health Service Grant 5X04 CA00184 (to C. F. B.) from the National Cancer Institute.
PY - 1978/3
Y1 - 1978/3
N2 - 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.
AB - 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.
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U2 - 10.1016/S0008-6215(00)84489-4
DO - 10.1016/S0008-6215(00)84489-4
M3 - Article
AN - SCOPUS:0004546447
SN - 0008-6215
VL - 61
SP - 291
EP - 299
JO - Carbohydrate Research
JF - Carbohydrate Research
IS - 1
ER -