1: Biochim Biophys Acta  1981 Sep 21;647(1):7-17 

The effect of cytochrome oxidase on lipid chain dynamics. A nanosecond
fluorescence depolarization study.

Kinosita K Jr, Kawato S, Ikegami A, Yoshida S, Orii Y.

Molecular motions in membranes composed of purified cytochrome oxidase (EC
1.9.3.1) and synthetic lipid (L-alpha-dimyristoylphosphatidylcholine or
L-alpha-dioleoylphosphatidylcholine) at various ratios were investigated with a
lipophilic fluorescent probe 1,6-diphenyl-1,3,5-hexatriene. Nanosecond
fluorescence depolarization kinetics of the probe showed that the rod-shaped
probe molecules perform a fast wobbling motion (restricted rotation) in all
membranes studied, presumably reflecting the motion of lipid acyl chains. At
temperatures where the pure lipid was in the liquid-crystalline phase, presence
of cytochrome oxidase reduced the angular range of the wobbling motion, whereas
its rate, the wobbling diffusion constant, was unaffected. On the other hand,
incorporation of the protein into lipid in the gel phase resulted in the
increase in the wobbling diffusion constant while the range of the wobbling
motion remained the same. A time-dependent view of lipid dynamics that accounts
for the above findings, as well as the results of recent electron spin resonance
and nuclear spin resonance studies of protein-lipid interactions, is proposed.

PMID: 6271207 [PubMed - indexed for MEDLINE]