1: Adv Biophys  1984;17:147-203 

Dynamic structure of biological and model membranes: analysis by optical
anisotropy decay measurement.

Kinosita K Jr, Kawato S, Ikegami A.

Rotational Brownian motion of molecules in membranes can be "visualized" by
time-resolved measurement of the decay of anisotropy of various flash-induced
optical signals, such as fluorescence, phosphorescence, delayed fluorescence,
transient absorption, or fluorescence depletion. The basic principles of the
various forms of anisotropy measurement are illustrated in a unified manner. In
organized structures such as membranes, rotational motion is restricted in
angular range. Methods of analysis of observed optical anisotropy decays for the
case of restricted rotation are described; the emphasis is laid on the separate
estimation of the two important parameters, the range and rate, that
characterize the restricted rotation. Practical aspects of the analytical
procedures are also discussed. As an example of application, recent work from
the authors' laboratory is reviewed: dynamic structures of lipid hydrocarbon
chain region of membranes have been revealed by time-resolved fluorescence
depolarization studies. A lipophilic fluorescent probe
1,6-diphenyl-1,3,5-hexatriene was incorporated in model and biological membranes
of known compositions. The decay of fluorescence anisotropy indicated that the
rod-shaped probe molecules wobbled in the membranes with a wobbling diffusion
constant around 0.1 rad2/nsec, presumably reflecting the dynamics of surrounding
lipid chains. The effects of temperature, ions, lipid chain unsaturation,
cholesterol, and protein on the range and rate of wobbling were examined with
model membranes. The dynamic structure of biological membranes was found to be
basically similar to that of the bilayer of unsaturated phospholipid; proteins
and cholesterol act mainly as barriers that reduce the angular range of wobbling
motion.

Publication Types:
Review

PMID: 6399815 [PubMed - indexed for MEDLINE]