Interaction between pullulanase from Klebsiella pneumoniae and cyclodextrins.
The interaction between pullulanase from Klebsiella pneumoniae and alpha-, beta-, and gamma-cyclodextrins and 6-O-alpha-glucosyl-alpha-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin was examined by means of inhibition studies of the enzyme activity, UV difference spectroscopy, and flow calorimetry. All the above cyclodextrins were found to be competitive inhibitors, but beta-cyclodextrin and 6-O-alpha-glucosyl-beta-cyclodextrin showed strong inhibition, the inhibitor constants being two orders of magnitude less than those of alpha- and gamma-cyclodextrins. The difference spectra of beta-cyclodextrin were slightly but significantly different from those of the other cyclodextrins, showing blue shift of a few nanometers. Moreover, only beta-cyclodextrin has a positive entropy change upon binding with the enzyme; all the other cyclodextrins have negative values. These results show that the binding mode of beta-cyclodextrin is subtly different from those of alpha- and gamma-cyclodextrins.
Iwamoto
H
H
Department of Food Science and Technology, Faculty of Engineering, Fukuyama University, Hiroshima.
Ohmori
M
M
Ohno
M
M
Hirose
J
J
Hiromi
K
K
Fukada
H
H
Takahashi
K
K
Hashimoto
H
H
Sakai
S
S
D002151:Calorimetry; D003505:Cyclodextrins / Q000378:metabolism* / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
D003505:Cyclodextrins; D006026:Glycoside Hydrolases; C100181:pullulanase