Ferrari R P, Traversa S, De Gioia L, Fantucci P, Suriano G, Ghibaudi E M
Dipartimento di Chimica I.F.M., Università di Torino, Turin, Italy.
J Biol Inorg Chem. 1999 Feb;4(1):12-20. doi: 10.1007/s007750050284.
Binding affinities to lactoperoxidase (LPO) of a homologous series of substituted catechol(amine)s [such as catechol, 4-methylcatechol, 3,4-dihydroxybenzoic acid, 3,4-dihydroxyphenylacetic acid, 3-(3,4-dihydroxyphenyl)propionic acid; dopamine, noradrenaline, adrenaline; L-3,4-dihydroxyphenylalanine] were studied by UV-visible spectroscopy and docking simulations. Dissociation constant (Kd) values were calculated by direct fitting of the experimental data and fall in a range of 3-95 mM. Thermodynamic parameters are comparable with those reported for the interaction of LPO with p-substituted phenols, suggesting a similar general mode of binding. Furthermore, the relative contributions to binding energy, described by the unimolecular constant Ku, show that interaction between protein and ligands originates from a relatively large number of groups. Docking and molecular dynamics simulations, in agreement with experimental evidence, predict that the substrate is localized into the access channel in the vicinity of heme distal pocket. This channel is characterized by a hydrophobic patch (six Phe residues) and by a charged contribution (two Glu and one His residues). All of the substrates, except caffeic acid, may approach the protein active site. Positively charged Arg372 acts as a gate above the heme distal pocket and seems to address substrate orientation in relation to the side-chain terminal group.
通过紫外可见光谱和对接模拟研究了一系列取代邻苯二酚（胺）[如邻苯二酚、4-甲基邻苯二酚、3,4-二羟基苯甲酸、3,4-二羟基苯乙酸、3-(3,4-二羟基苯基)丙酸；多巴胺、去甲肾上腺素、肾上腺素；L-3,4-二羟基苯丙氨酸]与乳过氧化物酶（LPO）的结合亲和力。通过对实验数据的直接拟合计算解离常数（Kd）值，其范围为3-95 mM。热力学参数与报道的LPO与对取代酚相互作用的参数相当，表明存在相似的一般结合模式。此外，由单分子常数Ku描述的对结合能的相对贡献表明，蛋白质与配体之间的相互作用源于相对大量的基团。与实验证据一致的对接和分子动力学模拟预测，底物位于血红素远端口袋附近的进入通道中。该通道的特征是有一个疏水区域（六个苯丙氨酸残基）和一个带电区域（两个谷氨酸和一个组氨酸残基）。除咖啡酸外，所有底物都可能接近蛋白质活性位点。带正电荷的精氨酸372在血红素远端口袋上方起门控作用，似乎决定了底物相对于侧链末端基团的取向。
