α-Amylase specificity for α-1,4-glycosidic bonds in amylopectin

Steps:

• Amylopectin consists of glucose units linked by α-1,4-glycosidic bonds in linear chains and α-1,6 bonds at branch points.
• α-Amylase acts as an endo-enzyme, cleaving internal α-1,4 linkages to produce maltose and dextrins.
• It stops at branch points, unable to hydrolyze α-1,6 bonds.
• Thus, the hydrolyzable bond in amylopectin is the α-1,4 type.

Why C is correct:

• α-Amylase hydrolyzes only α-1,4-glycosidic bonds, as defined by its enzymatic specificity for starch-like polysaccharides.

Why the others are wrong:

• A: α-1,6 bonds form branches in amylopectin and require debranching enzymes like amylo-1,6-glucosidase.
• B: β-1,4 bonds occur in cellulose and are hydrolyzed by β-amylase or cellulases, not α-amylase.
• D: β-1,6 bonds are rare in amylopectin and not targeted by α-amylase, which is specific to α-linkages.

Final answer: C