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

Abstract

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 nativemore » 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.« less

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
944782
Report Number(s):
PNNL-SA-61711
Journal ID: ISSN 0021-9797; JCISA5; 13890; KP1504020; TRN: US200902%%948
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
Journal of Colloid and Interface Science, 303(2):404-414
Additional Journal Information:
Journal Volume: 303; Journal Issue: 2; Journal ID: ISSN 0021-9797
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; ADSORPTION; BIOREMEDIATION; CYTOCHROMES; ELECTROSTATICS; HEMATITE; HEME; KINETICS; METALLOPROTEINS; METHIONINE; OXIDES; PHOSPHATES; PROTEINS; SORPTION; Adsorption; Phosphate; Cytochrome c; Conformation change; Hematite; Oxide; Environmental Molecular Sciences Laboratory

Citation Formats

Khare, Nidhi, Eggleston, Carrick M, Lovelace, David M, and Boese, Steven. Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces. United States: N. p., 2006. Web. doi:10.1016/j.jcis.2006.07.070.
Khare, Nidhi, Eggleston, Carrick M, Lovelace, David M, & Boese, Steven. Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces. United States. doi:10.1016/j.jcis.2006.07.070.
Khare, Nidhi, Eggleston, Carrick M, Lovelace, David M, and Boese, Steven. Tue . "Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces". United States. doi:10.1016/j.jcis.2006.07.070.
@article{osti_944782,
title = {Structural and redox properties of mitochondrial cytochrome c co-sorbed with phosphate on hematite (α-Fe2O3) surfaces},
author = {Khare, Nidhi and Eggleston, Carrick M and Lovelace, David M and Boese, Steven},
abstractNote = {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.},
doi = {10.1016/j.jcis.2006.07.070},
journal = {Journal of Colloid and Interface Science, 303(2):404-414},
issn = {0021-9797},
number = 2,
volume = 303,
place = {United States},
year = {2006},
month = {8}
}