Comparative studies on beta-glucan hydrolases. Isolation and characterization of an exo(1 yields 3)-beta-glucanase from the snail, Helix pomatia. |
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Authors: | J J Marshall R J Grand |
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Affiliation: | 1. Department of Chemistry, Royal Holloway College (University of London), Englefield Green, Surrey TW20 OEX, England;2. Laboratories for Biochemical Research, Howard Hughes Medical Institute, Miami, Florida 33152 USA;3. Department of Biochemistry, University of Miami School of Medicine, Miami, Florida 33152 USA |
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Abstract: | An exo-β-glucan hydrolase, present in the digestive juice of the snail, Helix pomatia, has been purified to homogeneity by chromatography on Bio-Gel P-60, Sephadex G-200, DEAE-cellulose, and DEAE-Sephadex. The enzyme degrades β-(1 → 3)-linked oligosaccharides and polysaccharides, rapidly and to completion, or near completion, yielding glucose as the major product of enzyme action. Mixed linkage (1→3; 1→4)-β-glucans are also extensively degraded and β-(1→6)- and β-(1→4)-linked glucose polymers are slowly degraded by the enzyme. This enzyme differs from other exo-β-glucanases, reported previously, in the broadness of its substrate specificity. The Km values for action on laminarin and lichenin are respectively 1.22 and 2.22 mg/ml; the maximum velocity of action on laminarin is approximately twice that on lichenin. The enzyme has a molecular weight of 82,000 as determined by polyacrylamide gel electrophoresis. Maximum activity is exhibited at pH 4.3 and at temperatures of 50–55 °C. |
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Keywords: | Address enquiries and reprint requests to J. J. Marshall Department of Biochemistry University of Miami School of Medicine P.O. Box 520875 Biscayne Annex Miami FL 33152. |
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