Masuoka Noriyoshi, Kubo Isao
Department of Biochemistry, Okayama University Graduate School of Medicine and Dentistry, 2-5-1 Shikatacho, Okayama 700-8558, Japan.
Biochim Biophys Acta. 2004 Apr 5;1688(3):245-9. doi: 10.1016/j.bbadis.2003.12.010.
Anacardic acid, 6[8(Z), 11(Z), 14-pentadecatrienyl]salicylic acid, inhibits generation of superoxide radicals by xanthine oxidase. This inhibition does not follow a hyperbolic inhibition, depends on anacardic acid concentrations, but follows a sigmoidal inhibition. The inhibition was analyzed by using a Hill equation, and slope factor and EC(50) were 4.3+/-0.5 and 53.6+/-5.1 microM, respectively. In addition, anacardic acid inhibited uric acid formation by xanthine oxidase cooperatively. Slope factor and EC(50) were 1.7+/-0.5 and 162+/-10 microM, respectively. The results indicate that anacardic acid binds to allosteric sites near the xanthine-binding domain in xanthine oxidase. Salicylic acid moiety and alkenyl side chain in anacardic acid are associated with the cooperative inhibition and hydrophobic binding, respectively.
腰果酚酸，即6-[8(Z), 11(Z), 14-十五碳三烯基]水杨酸，可抑制黄嘌呤氧化酶产生超氧阴离子自由基。这种抑制作用不遵循双曲线抑制规律，取决于腰果酚酸的浓度，而是遵循S形抑制规律。采用希尔方程对该抑制作用进行分析，斜率因子和半数有效浓度（EC50）分别为4.3±0.5和53.6±5.1微摩尔。此外，腰果酚酸协同抑制黄嘌呤氧化酶生成尿酸。斜率因子和EC50分别为1.7±0.5和162±10微摩尔。结果表明，腰果酚酸与黄嘌呤氧化酶中黄嘌呤结合结构域附近的变构位点结合。腰果酚酸中的水杨酸部分和烯基侧链分别与协同抑制和疏水结合有关。
