Tomková A, Antalík M, Bágel'ová J, Miskovský P, Ulicný J
Department of Nuclear Physics and Biophysics, Faculty of Sciences, Safárik University, Kosice, Czechoslovakia.
Gen Physiol Biophys. 1992 Jun;11(3):273-86.
Absorption UV-VIS and pre-resonance Raman spectra of acidic cyt c solutions with a series of thiols added (thiophenol, n-propanethiol, isopropanethiol, L-cysteine, dithiothreitol, 2-mercaptoethanol, N-acetyl-L-cysteine, p-acetamidothiophenol, 2-mercaptoethanamine, thioglycolic acid and mercaptopropionic acid), are presented. Interactions of cyt c molecule with the thiols were studied with the aim to identify binding of the thiols with the cyt c heme as its iron axial ligands. Absorption and Raman spectra showed some correlation between maxima of 700 nm region absorption band (typical for Fe-S axial bond in cyt c heme) and also wave numbers of spin state marker and axial ligand sensitive Raman bands on one, and pKa constant values of appropriate thiols on the other hand. These results imply thiol replacement of Met-80 from axial bond with heme iron and suggest that the force of Fe-L-cysteine axial bond is very close to the native axial bond (Fe-Met) for cyt c in neutral solution.
本文展示了添加一系列硫醇（苯硫酚、正丙硫醇、异丙硫醇、L-半胱氨酸、二硫苏糖醇、2-巯基乙醇、N-乙酰-L-半胱氨酸、对乙酰氨基苯硫酚、2-巯基乙胺、巯基乙酸和巯基丙酸）的酸性细胞色素c溶液的紫外-可见吸收光谱和预共振拉曼光谱。研究了细胞色素c分子与硫醇的相互作用，目的是确定硫醇作为铁轴向配体与细胞色素c血红素的结合情况。吸收光谱和拉曼光谱显示，一方面，700nm区域吸收带的最大值（细胞色素c血红素中Fe-S轴向键的典型特征）以及自旋态标记和轴向配体敏感拉曼带的波数，与另一方面相应硫醇的pKa常数之间存在一定相关性。这些结果表明硫醇取代了与血红素铁轴向键合的甲硫氨酸80，并表明在中性溶液中，细胞色素c的Fe-L-半胱氨酸轴向键的强度与天然轴向键（Fe-Met）非常接近。
