Identification of key amino acid residues in Neisseria polysaccharea amylosucrase |
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Authors: | Sarçabal P Remaud-Simeon M Willemot R Potocki de Montalk G Svensson B Monsan P |
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Affiliation: | Centre de Bioingénierie Gilbert Durand, UMR CNRS 5504, UR INRA 792, INSA, 135 Avenue de Rangueil, 31 077 Toulouse Cedex 4, France. |
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Abstract: | Amylosucrase from Neisseria polysaccharea catalyzes the synthesis of an amylose-like polymer from sucrose. Sequence alignment revealed that it belongs to the glycoside hydrolase family 13. Site-directed mutagenesis enabled the identification of functionally important amino acid residues located at the active center. Asp-294 is proposed to act as the catalytic nucleophile and Glu-336 as general acid base catalyst in amylosucrase. The conserved Asp-401, His-195 and His-400 residues are critical for the enzymatic activity. These results provide strong support for the predicted close structural and functional relationship between the sucrose-glucosyltransferases and enzymes of the alpha-amylase family. |
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