KCS Publications

HOME > Search > Browsing(BKCS) > Archives

Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 26, Number 2
BKCSDE 26(2)
February 20, 2005

Title	Characterization of the Catalytic Properties of Recombinant Acetohydroxyacid Synthase from Tobacco
Author	Joungmok Kim, Jung-Do Choi, Bok-Hwan Kim, Moon-Young Yoon*
Keywords	Acetohydroxyacid synthase, Kinetics, Fluorescence, Tobacco
Abstract	The nature of the active site of Tobacco acetohydroxyacid synthase (AHAS) in the substrate- and cofactorbinding was studied by kinetics and fluorescence spectroscopy. The substrate saturation curve does not follow Michaelis-Menten kinetics at different temperatures (7, 21 and 37 oC), pH (6.5, 7.5 and 8.5) and buffers (Tris- HCl and MOPS). The concentration of one half of the maximum velocity (S0.5) decreased in the following order: pyruvate > ThDP ? Mg+2 > FAD. However, the catalytic efficiency (Kcat/S0.5) inversely decreased in the following order; FAD > Mg+2 ? ThDP > pyruvate, indicating that the cofactors by in decreasing order; FAD, Mg+2, ThDP, affect the catalysis of AHAS. The dissociation constant (Kd) of the intrinsic tryptophan fluorescence decreased with the same tendency of the concentration of one half of the maximum velocity (S0.5) decreasing order. This data provides evidence that the substrate and cofactor binding natures of the active site, as well as its activation characteristics, resemble those of other ThDP-dependent enzymes.
Page	260 - 264
Full Text	PDF

How to access to the WOL for The Bulletin of the Korean Chemical Society ?

The Bulletin of the Korean Chemical Society will be co-published with Wiley-VCH from 2015 towards. The online version of the Journal will thus be available on Wiley Online Library, Wiley(-VCH)'s global online platform.

KCS members can get a free online access to the Bulletin of the Korean Chemical Society in WOL.

Free Access to WOL