1 April 1992 Site-to-site diffusion in proteins as observed by energy transfer and frequency-domain fluorometry
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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.
© (1992) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Joseph R. Lakowicz, Joseph R. Lakowicz, Ignacy Gryczynski, Ignacy Gryczynski, Jozef Kusba, Jozef Kusba, Wieslaw M. Wiczk, Wieslaw M. Wiczk, Henryk Szmacinski, Henryk Szmacinski, Michael L. Johnson, 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); doi: 10.1117/12.58215; https://doi.org/10.1117/12.58215

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