Department of Chemistry and Biochemistry, Presidency University, Kolkata 700073, India.
J Phys Chem A. 2012 Aug 16;116(32):8303-12. doi: 10.1021/jp304405u. Epub 2012 Aug 3.
A ternary system consisting of a protein, catechin (either + or - epimer), and Tb(III) in suitable aqueous buffer medium at physiological pH (= 6.8) has been shown to exhibit highly efficient "antenna effect". Steady state and time-resolved emission studies of each component in the binary complexes (protein with Tb(III) and (+)- or (-)-catechin with Tb(III)) and the ternary systems along with the molecular docking studies reveal that the efficient sensitization could be ascribed to the effective shielding of microenvironment of Tb(III) from O-H oscillator and increased Tb-C (+/-) interaction in the ternary systems in aqueous medium. The ternary system exhibits protein-mediated efficient antenna effect in D(2)O medium due to synergistic ET from both the lowest ππ* triplet state of Trp residue in protein and that of catechin apart from protection of the Tb(III) environment from matrix vibration. The simple system consisting of (+)- or (-)-catechin and Tb(III) in D(2)O buffer at pH 6.8 has been prescribed to be a useful biosensor.
在生理 pH 值（=6.8）的适当水缓冲介质中，由蛋白质、儿茶素（+或-表儿茶素）和 Tb(III)组成的三元体系表现出高效的“天线效应”。对二元配合物（蛋白质与 Tb(III)以及（+）-或（-）-儿茶素与 Tb(III)）和三元体系中每个组分的稳态和时间分辨发射研究以及分子对接研究表明，有效的敏化作用可归因于 Tb(III)的微环境从 O-H 振荡器中有效屏蔽，并增加了三元体系中 Tb-C（+/-）相互作用在水溶液中。三元体系在 D(2)O 介质中表现出蛋白质介导的高效天线效应，这是由于蛋白质中色氨酸残基的最低ππ三重态和儿茶素的ππ三重态协同 ET 作用，以及保护 Tb(III)环境免受基质振动的影响。在 pH 值为 6.8 的 D(2)O 缓冲液中由（+）-或（-）-儿茶素和 Tb(III)组成的简单体系被规定为一种有用的生物传感器。
