J. Biol. Chem., Vol. 260, Issue 8, 5175-5178, 04, 1985
Complex formation between flavodoxin and cytochrome c. Cross-linking studies
JL Dickerson, JJ Kornuc and DC Rees
Complex formation between Azotobacter vinelandii flavodoxin and horse
cytochrome c has been demonstrated through cross-linking studies with
dimethyl suberimidate, dimethyl adipimidate, 1-ethyl-3-(3-di-
methylaminopropyl)carbodiimide, and dimethyl-3,3'- dithiobispropionimidate.
Essentially quantitative cross-linking of cytochrome c and flavodoxin was
observed at low ionic strengths with the carbodiimide cross-linking
reagent. An association constant of 4 X 10(4) M-1 was obtained between
cytochrome c and flavodoxin at 88 mM ionic strength from analysis of the
cross-linking studies. This value is similar to the association constant
determined kinetically during the electron transfer reaction between
cytochrome c and flavodoxin (Simondsen, R.P., Weber, P.C., Salemme, F.R.,
and Tollin, G. (1982) Biochemistry 21, 6366-6375), and suggests that the
cross-linked complex may be similar to the precursor complex identified
kinetically. A structural model for the flavodoxin-cytochrome c complex
proposed by these workers is shown to be compatible with the present
cross-linking results.