Study Of The Specificity Of Xanthene Dye Binding To Mitochondria

James R. Bunting; Eleanor Kamali; Trung V. Phan; Robert M. Dowben; J. Lester Matthews

doi:10.1117/12.960185

17 March 1989 Study Of The Specificity Of Xanthene Dye Binding To Mitochondria

James R. Bunting, Eleanor Kamali, Trung V. Phan, Robert M. Dowben, J. Lester Matthews

Proceedings Volume 0997, Advances in Photochemotherapy; (1989) https://doi.org/10.1117/12.960185
Event: O-E/Fiber LASE '88, 1988, Boston, MA, United States

Abstract

The binding of Rhodamine 123 (Rh123), Rhodamine 6G (R6G), and Rhodamine B (RhB) (from the cationic xanthene series) to isolated rat liver mitochondria maintained in State IV respiration in the presence of rotenone (NADH oxidase inhibitor) was monitored by following changes in the fluorescence signal of the dyes. Rh123 and Rh6G bind strongly with quenching, to 0.25 and 0.20, respectively, and red shift of emission maxima by 10 nm. RhB binds much less potently with slight emission enhancement of 1.2. For Rh123 added to 0.5 mg/ml mitochondria' protein, a sigmoidal relationship is obtained between percentage fluorescence quenching and log of Rh123 concentration with a 50% inflection point of 3.5x10-6M, estimating an apparent association constant of 2.9x 105M-1 for Rh123 binding. Addition of 7 uM RhB during Rh123 titration moves the sigmoidal inflection point to higher Rh123 concentrations, suggesting either RhB enhancement of binding of Rh123 fluorescence quenching by energy transfer to RhB bound. These results suggest that, to a great degree, the binding of the xanthene dyes to mitochondrial sites is specific, competitive, and probably cooperative.

Citation Download Citation

James R. Bunting, Eleanor Kamali, Trung V. Phan, Robert M. Dowben, and J. Lester Matthews "Study Of The Specificity Of Xanthene Dye Binding To Mitochondria", Proc. SPIE 0997, Advances in Photochemotherapy, (17 March 1989); https://doi.org/10.1117/12.960185

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