THESIS

(also called α-dextrinase) which hydrolyses α-(1, 6) bonds of isomaltose and α-
dextrins) continue the digestive process and thus covert available starch to glucose
(Hayashida et al. 1990). A representation of amylase and debranching enzyme
hydrolysis of starch is shown schematically in Figure 11. The figure described that β-
amylase is an exo-acting enzyme cleaving successive, β-maltose molecules from the
non-reducing end of amylose or from the outer branches of amylopectin; it cannot by-
pass α-(1,6) bonds. While α-amylase is an endo-acting enzyme hydrolysis α-(1,4)
bonds at random giving rise to malto-oligosaccharides (linear or branched, typically
DP ~2-6); it does not hydrolyze α-(1.6) bonds. Debranching enzymes (e.g.
isoamylase or pullulanase) specifically hydrolyze α-(1-6) bonds at the branching point
of amylopectin. Amyloglucosidase 9glucoamylase) is an exo- acting hydrolase which
releases single glucose molecules from the non-reducing end of α-(1-4)
oligosaccharide or polysaccharides. This enzyme is unique because it can hydrolyze
α-(1-6) branching points, converting starch completely to glucose (Tester et al. 2004).
Figure 11 Action patterns of hydrolytic enzymes on amylose and amylopectin
Source: Tester et al. (2004)
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