Kinetics and inhibition of cyclomaltodextrinase from alkalophilic Bacillus sp. I-5.
The cyclomaltodextrinase from alkalophilic Bacillus sp. I-5 (CDase I-5) was expressed in Escherichia coli and the purified enzyme was used for characterization of the enzyme action. The hydrolysis products were monitored by both HPLC and high-performance ion chromatography analysis that enable the kinetic analysis of the cyclomaltodextrin (CD)-degrading reaction. Analysis of the kinetics of cyclomaltodextrin hydrolysis by CDase I-5 indicated that ring-opening of the cyclomaltodextrin was the major limiting step and that CDase I-5 preferentially degraded the linear maltodextrin chain by removing the maltose unit. The substrate binding affinity of the enzyme was almost same for those of cyclomaltodextrins while the rate of ring-opening was the fastest for cyclomaltoheptaose. Acarbose and methyl 6-amino-6-deoxy-alpha-d-glucopyranoside were relatively strong competitive inhibitors with K(i) values of 1.24 x 10(-3) and 8.44 x 10(-1) mM, respectively. Both inhibitors are likely to inhibit the ring-opening step of the CD degradation reaction.
Kim
M J
MJ
Research Center for New Bio-Materials in Agriculture, Department of Food Science, Seoul National University, Suwon, 441-744, Korea.
Park
W S
WS
Lee
H S
HS
Kim
T J
TJ
Shin
J H
JH
Yoo
S H
SH
Cheong
T K
TK
Ryu
S
S
Kim
J C
JC
Kim
J W
JW
Moon
T W
TW
Robyt
J F
JF
Park
K H
KH
D020909:Acarbose / Q000494:pharmacology; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D003505:Cyclodextrins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D005960:Glucosides / Q000494:pharmacology; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
D003505:Cyclodextrins; D005960:Glucosides; D011994:Recombinant Proteins; C403593:methyl-6-amino-6-deoxyglucopyranoside; D006026:Glycoside Hydrolases; C048745:cyclomaltodextrinase; D020909:Acarbose