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Sökning: id:"swepub:oai:lup.lub.lu.se:7b3b7e70-1661-4580-bcba-e7a04ff59e79" > Tyrosine residues a...

Tyrosine residues as redox cofactors in human hemoglobin : implications for engineering nontoxic blood substitutes

Reeder, Brandon J (författare)
Grey, Marie (författare)
Lund University,Lunds universitet,Tillämpad biokemi,Centrum för tillämpade biovetenskaper,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Fysikalisk kemi,Enheten för fysikalisk och teoretisk kemi,Pure and Applied Biochemistry,Center for Applied Life Sciences,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH,Physical Chemistry,Physical and theoretical chemistry,Faculty of Engineering, LTH
Silaghi-Dumitrescu, Radu-Lucian (författare)
visa fler...
Svistunenko, Dimitri A (författare)
Bülow, Leif (författare)
Lund University,Lunds universitet,Tillämpad biokemi,Centrum för tillämpade biovetenskaper,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Pure and Applied Biochemistry,Center for Applied Life Sciences,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH
Cooper, Chris E (författare)
Wilson, Michael T (författare)
visa färre...
 (creator_code:org_t)
2008
2008
Engelska 8 s.
Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 283:45, s. 30780-30787
  • Tidskriftsartikel (refereegranskat)
Abstract Ämnesord
Stäng  
  • Respiratory proteins such as myoglobin and hemoglobin can, under oxidative conditions, form ferryl heme iron and protein-based free radicals. Ferryl myoglobin can safely be returned to the ferric oxidation state by electron donation from exogenous reductants via a mechanism that involves two distinct pathways. In addition to direct transfer between the electron donor and ferryl heme edge, there is a second pathway that involves "through-protein" electron transfer via a tyrosine residue (tyrosine 103, sperm whale myoglobin). Here we show that the heterogeneous subunits of human hemoglobin, the alpha and beta chains, display significantly different kinetics for ferryl reduction by exogenous reductants. By using selected hemoglobin mutants, we show that the alpha chain possesses two electron transfer pathways, similar to myoglobin. Furthermore, tyrosine 42 is shown to be a critical component of the high affinity, through-protein electron transfer pathway. We also show that the beta chain of hemoglobin, lacking the homologous tyrosine, does not possess this through-protein electron transfer pathway. However, such a pathway can be engineered into the protein by mutation of a specific phenylalanine residue to a tyrosine. High affinity through-protein electron transfer pathways, whether native or engineered, enhance the kinetics of ferryl removal by reductants, particularly at low reductant concentrations. Ferryl iron has been suggested to be a major cause of the oxidative toxicity of hemoglobin-based blood substitutes. Engineering hemoglobin with enhanced rates of ferryl removal, as we show here, is therefore likely to result in molecules better suited for in vivo oxygen delivery.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)
NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

Animals
Blood Substitutes
Electron Transport
Free Radicals
Hemoglobins
Horses
Humans
Iron
Kinetics
Myoglobin
Oxidation-Reduction
Oxygen
Protein Engineering
Protein Subunits
Sperm Whale
Tyrosine

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