Purification and Properties of Laminarin Hydrolases from the Ascidian, <i>Halocynthia roretzi</i>

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  • マボヤのラミナリン分解酵素の精製および特性について
  • マボヤ ノ ラミナリン ブンカイ コウソ ノ セイセイ オヨビ トクセイ ニ

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Laminarin hydrolase of the ascidian, Halocynthia roretzi, was found to comprise an endoglucanase (percentage activity, 23%), two exoglucosidases (20 and 42%), and a nonspecific β-glucosidase (15%). They were separated by DEAE-Sephadex chromatography followed by gel filtration.<br> Endoglucanase (laminarinase, EC 3. 2. 1. 6, or endo-1, 3-β-glucanase, EC 3. 2. 1. 39, mol. wt. 20, 000) produced oligosaccharides and glucose from laminarin, and exhibited maximum activity at pH 5.5. It was inhibited by iodoacetamide but not by glucono-1, 4-lactone. Vanadium pentoxide and ethylenediaminetetraacetic acid activated the enzyme.<br> Exoglucosidase (exo-1, 3-β-glucosidase, EC 3. 2. 1. 58) was separated into two enzymes. The one (mol. wt. 370, 000), exhibiting maximum activity at pH 6.5, was inhibited by glucono-1, 4-lactone but not by iodoacetamide, and activated by sodium chloride. The only reaction product was glucose. The other (mol. wt. 120, 000), showing maximum activity at pH 6.0, was inhibited by both glucono-1, 4-lactone and iodoacetamide. The main product was glucose, but a small quantity of biose was found in the reaction mixture.<br> Nonspecific β-glucosidase (EC 3. 2. 1. 21) also hydrolyzed laminarin to produce glucose at a slow rate. Its molecular weight was estimated to be 80, 000, and the optimum pH was 4.8.

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