Site-to-site diffusion in proteins as observed by energy transfer and frequency-domain fluorometry

Joseph R. Lakowicz; Ignacy Gryczynski; Jozef Kusba; Wieslaw M. Wiczk; Henryk Szmacinski; Michael L. Johnson

doi:10.1117/12.58215

1 April 1992 Site-to-site diffusion in proteins as observed by energy transfer and frequency-domain fluorometry

Joseph R. Lakowicz, Ignacy Gryczynski, Jozef Kusba, Wieslaw M. Wiczk, Henryk Szmacinski, Michael L. Johnson

Proceedings Volume 1640, Time-Resolved Laser Spectroscopy in Biochemistry III; (1992) https://doi.org/10.1117/12.58215
Event: OE/LASE '92, 1992, Los Angeles, CA, United States

Abstract

We report measurements of site-to-site diffusion in proteins, using frequency-domain measurements of time-dependent energy transfer. The possibility of such measurements is shown from simulations which demonstrate that donor-to-acceptor (D-to-A) diffusion alters the donor frequency response, and that this effect is observable in the presence of a distribution of distances. For decay times typical of tryptophan fluorescence, the simulations indicate D-to-A diffusion coefficients can be measured ranging from 10^-7 to 10^-5 cm²/s. This possibility was verified by studies of a methylene-chain linked D-A pairs in solutions of varying viscosity. D-to-A diffusion was also measured for acceptor-labeled melittin in the random coil and (alpha) -helical states. Unfolding of troponin I results in increased D-A diffusion. Surprisingly, more rapid diffusion was observed for melittin in the (alpha) -helical state, but over a limited range of distances.

Citation Download Citation

Joseph R. Lakowicz, Ignacy Gryczynski, Jozef Kusba, Wieslaw M. Wiczk, Henryk Szmacinski, and Michael L. Johnson "Site-to-site diffusion in proteins as observed by energy transfer and frequency-domain fluorometry", Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); https://doi.org/10.1117/12.58215

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