Localization and mobility of coenzyme Q in lipid bilayers and membranes
Article first published online: 16 DEC 2008
Copyright © 1999 International Union of Biochemistry and Molecular Biology, Inc.
Volume 9, Issue 2-4, pages 87–93, 1999
How to Cite
Lenaz, G., Fato, R., Di Bernardo, S., Jarreta, D., Costa, A., Genova, M. L. and Castelli, G. P. (1999), Localization and mobility of coenzyme Q in lipid bilayers and membranes. BioFactors, 9: 87–93. doi: 10.1002/biof.5520090202
- Issue published online: 16 DEC 2008
- Article first published online: 16 DEC 2008
- University of Bologna and by a CNR bilateral project and by PRIN “Bioenergetics and Membrane Transport” from MURST (Rome)
We have studied the mobility of coenzyme Q (CoQ) in lipid bilayers and mitochondrial membranes in relation to the control of electron transfer activities. A molecular dynamics computer simulation in the vacuum yielded a folded structure for CoQ10, with a length of only 21 Å. Using this information we were able to calculate diffusion coefficients in the range of 10−6 cm2/s in good agreement with those found experimentally by fluorescence quenching of pyrene derivatives. To investigate if CoQ diffusion may represent the rate-limiting step of electron transfer, we reconstituted complexes I and III and assayed the resulting NADH-cytochrome c reductase activity in presence of different CoQ10 levels and at different distances between complexes; the experimental turnovers were higher than the collision frequencies calculated using diffusion coefficients of 10−9 cm2/s but compatible with values found by us by fluorescence quenching. Since the experimental turnovers are independent of the distance between complexes, we conclude that CoQ diffusion is not rate-limiting for electron transfer.