The Protein Journal

, Volume 26, Issue 4, pp 257–263

Temperature Dependent Soret Spectral Band Shifts Accompany Human CN-Mesohemoglobin Assembly

  • Priyani  V. Fonseka
  • Gayathri Vasudevan
  • Lisa-Jo  Ann Clarizia
  • Melisenda  J. McDonald
Article

DOI: 10.1007/s10930-006-9067-7

Cite this article as:
Fonseka, P.V., Vasudevan, G., Clarizia, LJ.A. et al. Protein J (2007) 26: 257. doi:10.1007/s10930-006-9067-7

Abstract

The interaction between human apohemoglobin A and CN-Mesohemin, a monomeric non-native heme derivative, was probed by Soret spectrophotometric titrations in 0.05 M potassium phosphate buffer, pH 7 at varied temperatures. Hypsochromic shifts in the absorbance maxima were observed at all temperatures below 10°C. First derivative spectroscopy of CN-Mesohemin titrations was used to provide further evidence of a spectral shift upon CN-Mesohemoglobin assembly. Findings of Soret Spectral shifts demonstrate a preference for the α chain heme site by CN-Mesohemin indicative of semi-α-hemoglobin intermediate formation. CN-Mesohemin, a derivative with peripheral 2,4 ethyl groups, does not possess the extended conjugation seen for native CN-Protohemin with its 2,4 vinyl groups. Indeed, reduced polarity of CN-Mesohemin over that of CN-Protohemin resulted in distinct temperature dependencies. Molecular visualization and protein-ligand interaction analysis targeted a functionally diverse residue unique to the α-chain. Tyrosine-42 (a polar/non-polar amino acid) appeared to play a prominent role in the assembly process.

Keywords

Apohemoglobin A CN-Mesohemin protein–ligand interactions Soret region 

Copyright information

© Springer Science+Business Media, LLC 2006

Authors and Affiliations

  • Priyani  V. Fonseka
    • 1
    • 2
  • Gayathri Vasudevan
    • 1
    • 3
  • Lisa-Jo  Ann Clarizia
    • 1
  • Melisenda  J. McDonald
    • 1
  1. 1.Department of ChemistryUniversity of MassachusettsLowellUSA
  2. 2.Columbus Children’s Hospital Research InstituteColumbusUSA
  3. 3.Department of ChemistryWellesley CollegeWellesleyUSA

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