Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces

Journal Article · Tue Aug 01 04:00:00 EDT 2006 · Journal of Colloid and Interface Science, 303(2):404-414

DOI:https://doi.org/10.1016/j.jcis.2006.07.070· OSTI ID:944782

Khare, Nidhi; Eggleston, Carrick M; Lovelace, David M; Boese, Steven

The interaction of metalloproteins with oxides has implications not only for bioanalytical systems and biosensors but also in the areas of biomimetic photovoltaic devices, bioremediation, and bacterial metal reduction. Here, we investigate mitochondrial ferricytochrome c (Cyt c) co-sorption with 0.01 and 0.1 M phosphate on hematite (α-Fe2O3) surfaces as a function of pH (2–11). Although Cyt c sorption to hematite in the presence of phosphate is consistent with electrostatic attraction, other forces act upon Cyt c as well. The occurrence of multilayer adsorption, and our AFM observations, suggest that Cyt c aggregates as the pH approaches the Cyt c isoelectric point. In solution, methionine coordination of heme Fe occurs only between pH 3 and 7, but in the presence of phosphate this coordination is retained up to pH 10. Electrochemical evidence for the presence of native Cyt c occurs down to pH 3 and up to pH 10 in the absence of phosphate, and this range is extended to pH 2 and 11 in the presence of phosphate. Cyt c that initially adsorbs to a hematite surface may undergo conformation change and coat the surface with unfolded protein such that subsequently adsorbing protein is more likely to retain the native conformational state. AFM provides evidence for rapid sorption kinetics for Cyt c co-sorbed with 0.01 or 0.1 M phosphate. Cyt c co-sorbed with 0.01 M phosphate appears to unfold on the surface of hematite while Cyt c co-sorbed with 0.1 M phosphate possibly retains native conformation due to aggregation.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 944782
• Report Number(s): PNNL-SA-61711; 13890; KP1504020
• Journal Information: Journal of Colloid and Interface Science, 303(2):404-414, Journal Name: Journal of Colloid and Interface Science, 303(2):404-414 Journal Issue: 2 Vol. 303; ISSN 0021-9797; ISSN JCISA5
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ADSORPTION
Adsorption
BIOREMEDIATION
CYTOCHROMES
Conformation change
Cytochrome c
ELECTROSTATICS
Environmental Molecular Sciences Laboratory
HEMATITE
HEME
Hematite
KINETICS
METALLOPROTEINS
METHIONINE
OXIDES
Oxide
PHOSPHATES
PROTEINS
Phosphate
SORPTION