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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 29, Number 8
BKCSDE 29(8)
August 20, 2008 

Conformational and Structural Changes of Choline Oxidase from Alcaligenes Species by Changing pH Values
A. Hekmat, A. A. Saboury*, A. Divsalar, M. Khanmohammadi
Choline oxidase, pH, Chemometry analyses, Fluorescence quenching, Circular dichroism
Results of intrinsic and extrinsic fluorescence studies on choline oxidase revealed that the enzyme at high alkaline pH values has more accessible hydrophobic patches relative to acidic pH. Fluorescence quenching studies with acrylamide confirm these changes. The quenching constants were also determined at different pH(s) by using the Stern-Volmer equation. CD studies showed that at higher pH a transition from α-helix to β- structure was appeared while at lower pH the content of α-helix structure was increased. Furthermore, analysis of the spectral data using chemometric method gave evidence for existence of intermediate components at very high pH(s). Results of thermal denaturation evaluated that the enzyme has the most instability at higher pH(s). Altogether low and high pH values caused significant alteration on secondary and tertiary structures of choline oxidase via inducing of an intermediate.
1510 - 1518
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