Molecular Biology and Evolution, Vol 8, 545-558, Copyright © 1991 by Society for Molecular Biology and Evolution
WH Koppenol, JD Rush, JD Mills and E Margoliash
Vertebrate cytochromes c and the cytochromes c of insects and plants have,
on average, dipole moments of 320 and 340 debye, respectively. The
direction of the dipole vector with respect to the haem plane, at the
solvent-accessible edge of which electron transfer presumably takes place,
is conserved in these two groups--at 32 degrees +/- 7 degrees and 22
degrees +/- 10 degrees, respectively. The variation of dipole orientations
and magnitudes observed in these species is compared with the results of a
model in which charge distributions occur randomly. Since this model does
not generate the observed charge asymmetries of the various cytochromes c,
it is concluded that the dipole moment of cytochrome c is a feature that is
evolutionarily conserved, apparently because it has an important influence
on the interaction of this mobile electron carrier with its physiological
electron donors and acceptors in the intermembrane space of mitochondria.
ORIGINAL ARTICLE
The dipole moment of cytochrome c [published erratum appears in Mol Biol Evol 1991 Nov;8(6):904]
Biodynamics Institute, Louisiana State University, Baton Rouge 70803- 1800.
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