Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran.
J Enzyme Inhib Med Chem. 2010 Apr;25(2):272-81. doi: 10.1080/14756360903179351.
A novel monofunctional benzyldithiocarbamate, C(6)H(5)CH(2)NHCSSNa (I), and a bifunctional p-xylidine-bis(dithiocarbamate), NaSSCNHCH(2)C(6)H(4)CH(2)NHCSSNa (II), as sodium salts, were synthesized by reaction between p-xylylenediamine or benzylamine with CS(2) in the presence of NaOH. They were characterized by spectroscopic techniques such as (1)H NMR, IR, and elemental analysis. These water-soluble compounds were examined for their inhibition of both activities of mushroom tyrosinase (MT) from a commercial source of Agricus bisporus. l-3,4- Dihydroxyphenylalanine (L-DOPA) and l-tyrosine were used as natural substrates for the catecholase and cresolase enzyme reactions, respectively. Kinetic studies showed noncompetitive inhibition of I and mixed type inhibition of II on both activities of MT. The inhibition constant (K(I)) of II was smaller than that of I. Raising the temperature from 27 to 37 degrees C caused a decrease in K(I) values of I and an increase in values of II. The binding process for inhibition of I was only entropy driven, which means that the predominant interaction in the active site of the enzyme is hydrophobic; meanwhile, the electrostatic interaction can be important for the inhibition of II due to the enthalpy driven binding process. Fluorescence studies showed a decrease of emission intensity without a shift of emission maximum in the presence of different concentrations of compounds. An extrinsic fluorescence study did not show any considerable change of the tertiary structure of MT. Probably, the conformation of inhibitor-bound MT is stable and inflexible compared with uninhibited MT.
一种新型的单官能苄基二硫代氨基甲酸盐 C(6)H(5)CH(2)NHCSSNa (I) 和一种双官能对二甲苯-双(二硫代氨基甲酸盐)，NaSSCNHCH(2)C(6)H(4)CH(2)NHCSSNa (II)，作为钠盐，是通过在 NaOH 存在下，用 CS(2)与对二甲苯二胺或苄胺反应合成的。它们的结构通过光谱技术，如 (1)H NMR、IR 和元素分析来表征。这些水溶性化合物被用于抑制蘑菇酪氨酸酶 (MT) 的两种活性，该 MT 来源于商业来源的双色蘑菇 (Agicus bisporus)。L-3,4-二羟基苯丙氨酸 (L-DOPA) 和 L-酪氨酸分别被用作儿茶酚酶和邻苯二酚酶反应的天然底物。动力学研究表明，I 对 MT 的两种活性表现为非竞争性抑制，而 II 则表现为混合性抑制。II 的抑制常数 (K(I)) 小于 I。将温度从 27 升高到 37 度，会导致 I 的 K(I) 值降低，而 II 的 K(I) 值升高。I 的抑制结合过程仅由熵驱动，这意味着在酶的活性部位，主要的相互作用是疏水的；而由于结合过程是由焓驱动的，静电相互作用对于 II 的抑制可能很重要。荧光研究表明，在存在不同浓度的化合物时，发射强度会降低，但发射峰没有位移。外源性荧光研究没有显示 MT 的三级结构发生任何明显变化。可能是与未受抑制的 MT 相比，抑制剂结合的 MT 的构象是稳定且不易弯曲的。
