Attempt at Affinity Labeling of α- and β-Amylases by α- and β-D-Glucopyranosides and α- and β-Maltooligosaccharides with 2, 3-Epoxypropyl Residue as Aglycone: Specific Inactivation of β-Amylases

Abstract

Among 2, 3-epoxypropyl α-D-glucopyranoside and 2, 3-epoxypropyl α-maltooligosaccharides and the β-anomers, 2, 3-epoxypropyl α-D-glucopyranoside (α-EPG) strongly inactivated the β-Jamylases [EC 3.2.1.2] of sweet potato, barley, and Bacillus cereus, in addition to soybean β-amylase [J. Biochem., 99, 1631 (1986)]. However, none of the compounds used inactivated any α-amylases [EC 3.2.1.1] of porcine pancreas, Aspergillus oryzae, or Bacillus amyloliquefaciens. Irreversible incorporation of ¹⁴C-labeled α-EPG into β-amylases was stoichiometric, i.e., one α-EPG per active site of the enzyme was bound, and the inactivations were almost complete. The results suggest that α-EPG is an affinity labeling reagent selective for β-amylase. Slow inactivations by the other compounds were also observed, depending on the difference of source of β-amylase.