Abstract
The oxidation of cytochrome f by the soluble cupredoxin plastocyanin
is a central reaction in the photosynthetic electron transfer chain
of all oxygenic organisms. Here, two different computational approaches
are used to gain new insights into the role of molecular recognition
and protein-protein association processes in this redox reaction.
First, a comparative analysis of the computed molecular electrostatic
potentials of seven single and multiple point mutants of spinach
plastocyanin (D42N, E43K, E43N, E43Q/D44N, E59K/E60Q, E59K/E60Q/E43N,
Q88E) and the wt protein was carried out. The experimentally determined
relative rates (k(2)) for the set of plastocyanin mutants are found
to correlate well (r(2) = 0.90 - 0.97) with the computed measure
of the similarity of the plastocyanin electrostatic potentials. Second,
the effects on the plastocyanin/cytochrome f association rate of
these mutations in the plastocyanin "eastern site" were evaluated
by simulating the association of the wild type and mutant plastocyanins
with cytochrome f by Brownian dynamics. Good agreement between the
computed and experimental relative rates (k(2)) (r(2) = 0.89 - 0.92)
was achieved for the plastocyanin mutants. The results obtained by
applying both computational techniques provide support for the fundamental
role of the acidic residues at the plastocyanin eastern site in the
association with cytochrome f and in the overall electron-transfer
process.
- 11720977
- binding,
- chemical,
- computer
- concentration,
- conformation,
- cytochromes
- cytochromes,
- electron
- electrostatics,
- f,
- gov't,
- hydrogen-ion
- ligands,
- models,
- molecular,
- mutation,
- non-u.s.
- oleracea,
- oxidation-reduction,
- oxygen,
- plastocyanin,
- point
- protein
- research
- simulation,
- spinacia
- support,
- transport,
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