Protein-Mediated Efficient Synergistic "Antenna Effect" in a Ternary System in D sub(2)O Medium

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2012-08, Vol.116 (32), p.8303-8312-8303-8312
• Main Authors: Ghorai, Shyamal Kr, Samanta, Swarna Kamal, Mukherjee, Manini, Ghosh, Sanjib
• Format: Article
• Language: English
• Subjects: Antennas; Biosensors; Catechins; Oscillators; Proteins; Ternary systems; Vibration
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp304405u

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 sub(2)O medium due to synergistic ET from both the lowest pi pi * 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 sub(2)O buffer at pH 6.8 has been prescribed to be a useful biosensor.