Rotational dynamics of surface probes in lipid vesicles

Krishna, M. M. G. ; Srivastava, Arvind ; Periasamy, N. (2001) Rotational dynamics of surface probes in lipid vesicles Biophysical Chemistry, 90 (2). 123-133 . ISSN 0301-4622

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Official URL: http://linkinghub.elsevier.com/retrieve/pii/S03014...

Related URL: http://dx.doi.org/10.1016/S0301-4622(01)00137-5

Abstract

Translational and rotational diffusion of fluorescent molecules on the surface of small biological systems such as vesicles, proteins and micelles depolarize the fluorescence. A recent study has treated the case of the translational dynamics of surface probes (M. M. G. Krishna, R. Das, N. Periasamy and R. Nityananda, J. Chem. Phys., 112 (2000) 8502-8514) using Monte Carlo and theoretical methods. Here we extend the application of the methodologies to apply the case of rotational dynamics of surface probes. The corresponding fluorescence anisotropy decays were obtained using the Monte Carlo simulation methods for the two cases: surface probes undergoing rotational dynamics on a plane and on a sphere. The results were consistent with the theoretical equations which show that Monte Carlo methods can be used to simulate the surface diffusion problems. The anisotropy decay for the rotational diffusion of a molecule on a planar surface is single exponential and the residual anisotropy is zero. However, residual anisotropy is finite for the case of rotational diffusion on a sphere because of the spatial averaging of the anisotropy function. The rotational correlation time in both the cases is (4Drot)-1 with Drot being the rotational diffusion coefficient. Rotational dynamics of a surface bound dye in a single giant liposome and in sonicated vesicles were studied and the results were explained according to the theoretical equations. A fast component of fluorescence depolarization was also observed for sonicated vesicles which was interpreted as wobbling-in-cylinder dynamics of the surface-bound dye.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Monte Carlo Simulation; Fluorescence Anisotropy; Fluorescence Microscopy; Giant Vesicle; Lipid Membrane; Surface Diffusion; Rotational Diffusion
ID Code:37530
Deposited On:22 Apr 2011 12:34
Last Modified:22 Apr 2011 12:34

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