Flavodoxin-cytochrome c interactions: circular dichroism and nuclear magnetic resonance studies

Journal Article · Tue Aug 11 04:00:00 EDT 1987 · Biochemistry; (United States)

DOI:https://doi.org/10.1021/bi00390a024· OSTI ID:5932493

Tollin, G; Brown, K; De Francesco, R; Edmondson, D E

Circular dichroism and /sup 1/H and /sup 31/P nuclear magnetic resonance spectroscopy have been used to investigate complex formation between cytochrome c and the flavodoxins from Azotobacter vinelandii and Clostridium pasteurianum. Such complexes are known to be involved in the mechanism of electron transfer between these two redox proteins. A large increase in ellipticity in the Soret band of the cytochrome heme was observed upon formation of the Clostridium flavodoxin complex, whereas much smaller changes were found for the complexes with either Azotobacter flavodoxin or an 8..cap alpha..-imidazolyl-FMN-substituted Clostridium flavodoxin analogue. Similarly, the magnitudes of the perturbations of the contact-shifted heme proton resonances obtained upon complexation of cytochrome c by Azotobacter flavodoxin were much smaller than those previously shown for Clostridium flavodoxin. /sup 31/P nuclear magnetic resonance measurements were also consistent with differences in the interactions between the components in the complexes of the two flavodoxins with cytochrome c. It is suggested that these spectral changes are due to a loosening or opening of the heme crevice upon Clostridium flavodoxin binding, which allows closer contact between the heme and flavin prosthetic groups and results in a faster rate of electron transfer. The implications of these observations for biological oxidation-reduction processes are considered.

• Research Organization: Emory Univ. School of Medicine, Atlanta, GA
• OSTI ID: 5932493
• Journal Information: Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:16; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
62 RADIOLOGY AND NUCLEAR MEDICINE
ACRIDINES
AMINES
AROMATICS
AZAARENES
AZINES
AZOTOBACTER
BACTERIA
BARYONS
CHEMICAL SHIFT
CLOSTRIDIUM
CONFIGURATION INTERACTION
CYTOCHROMES
DICHROISM
ELECTRON TRANSFER
ELEMENTARY PARTICLES
FERMIONS
FLAVINES
HADRONS
HETEROCYCLIC COMPOUNDS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
PIGMENTS
PROTEINS
PROTONS
PYRIDINES
RESONANCE
STABLE ISOTOPES