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BioFiles Volume 5, Number 5 — Enzymes and Reagents for Alternative Energy

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Table of Contents

 


Enzymes for Starch Analysis

Enzymatic hydrolysis of starch-based biomass to yield monomeric glucose is often a multienzyme process and can involve α-amylase, β-amylase, amyloglucosidase, isoamylase and α-glucosidase.

  • α-Amylase catalyzes the endohydrolysis of α-(1→4)-D-glucosidic linkages in polysaccharides containing three or more α-(1→4)-linked D-glucose units.
  • β-Amylase catalyzes the exohydrolysis of α-(1→4)-D-glucosidic linkages in polysaccharides resulting in the successive liberation of maltose units from the nonreducing ends of the chains.
  • Amyloglucosidase (glucoamylase) catalyzes the hydrolysis of terminal α-(1→4)-D-glucose residues successively from the non-reducing ends of maltooligo- and polysaccharides with release of β-D-glucose. Most forms of the enzyme can rapidly hydrolyze α-(1→6)-D-glucosidic bonds when the next bond in the sequence is 1→4- and some preparations of this enzyme hydrolyze 1→6- and 1→3-α-D-glucosidic bonds in other polysaccharides.
  • Isoamylase catalyzes the hydrolysis of α-(1→6)-D-glucosidic branch linkages in amylopectin and β-limit dextrins.
  • α-Glucosidase catalyzes the hydrolysis of terminal 1→4-linked α-D-glucose residues successively from the non-reducing ends of maltooligo- and to a lesser extent polysaccharides with release of β-D-glucose. Most forms of the enzyme can slowly hydrolyze α-(1→6)-D-glucosidic bonds.

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