Nakamaru Y
J Biochem. 1977 Nov;82(5):1189-95. doi: 10.1093/oxfordjournals.jbchem.a131805.
The mechanism of spectral shift and absorption intensity change of the divalent bromocresol purple (BCP) anion was further investigated and it was characterized as a spectrophotometric membrane probe. At high concentrations (1-40 mM), the absorption intensity of th BCP anion at 590 nm (monomer band) decreased markedly with increase of the dye concentration, while another absorption band appeared at 554 nm. Analysis of the change of absorption intensity showed that the mared decrease resulted from dimer formation of BCP (polymer formation at concentrations higher than 20 mM). Wavelengths of maximum absorption (lambdamax) of the BCP anion were determined in various solvents and comparison of these lambdamax's with lambdamax of the BCP anion bound to SR showed that the hydrophobicity of the area of BCP anion binding to SR corresponded to a refractive index of 1.429. While the BCP anion bound to SR showed a monomer spectrum, a dimer band appeared for the BCP anion bound to SR-Pi (phosphorylated protein) with a marked decrease in the absorption intensity at the monomer band, indicating that two polar groups, binding sites for the BCP anions, closely approached each other in the SR-Pi configuration.
对二价溴甲酚紫（BCP）阴离子的光谱位移和吸收强度变化机制进行了进一步研究，并将其表征为一种分光光度法膜探针。在高浓度（1 - 40 mM）下，BCP阴离子在590 nm处（单体带）的吸收强度随着染料浓度的增加而显著降低，同时在554 nm处出现另一个吸收带。对吸收强度变化的分析表明，显著降低是由于BCP形成二聚体（在浓度高于20 mM时形成聚合物）所致。在各种溶剂中测定了BCP阴离子的最大吸收波长（λmax），并将这些λmax与结合到SR上的BCP阴离子的λmax进行比较，结果表明BCP阴离子与SR结合区域的疏水性对应于折射率为1.429。虽然结合到SR上的BCP阴离子呈现单体光谱，但结合到SR-Pi（磷酸化蛋白）上的BCP阴离子出现了二聚体带，且单体带的吸收强度显著降低，这表明BCP阴离子的两个极性基团（结合位点）在SR-Pi结构中彼此紧密靠近。
