ISSN:
1432-1327
Keywords:
Flavodoxin Cytochrome Electron transfer Electrostatic Stopped-flow kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract. A hypothetical model for the non-physiological electron transfer complex between cytochrome c 553 (c 553) and the flavodoxin (fld) from the sulphate-reducing bacteria Desulfovibrio vulgaris has been recently published [1] based on rigid-body docking and refined by molecular dynamics. In this study, the functional validity of this model is tested by looking at the role of electrostatics in the non-physiological inter-protein electron transfer between the two proteins at different ionic strengths. The results are compared with the electron transfer between fld and cytochrome c from horse heart (hhc). Second-order rate constants (k2) were measured for both non-physiological systems at different ionic strengths: a complex, bell-shaped behaviour is observed for the k2 of the c 553/fld redox pair with an optimum rate at I=58 mmol l–1, whereas under the same conditions the k2 for hhc/fld decreased monotonically with increasing ionic strength. Results from the electron transfer kinetics are rationalised in terms of reorganisational effects of an ensemble of conformations of the electron transfer competent c 553/fld complexes, consistent with the published model.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s007750000162
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