Structural and thermodynamic consequences of b heme binding for monomeric apoglobins and other apoproteins

Gene. 2007 Aug 15;398(1-2):12-28. doi: 10.1016/j.gene.2007.02.046. Epub 2007 May 1.


The binding of a cofactor to a protein matrix often involves a reorganization of the polypeptide structure. b Hemoproteins provide multiple examples of this behavior. In this minireview, selected monomeric and single b heme proteins endowed with distinct topological properties are inspected for the extent of induced refolding upon heme binding. To complement the data reported in the literature, original results are presented on a two-on-two globin of cyanobacterial origin (Synechococcus sp. PCC 7002 GlbN) and on the heme-containing module of FixL, an oxygen-sensing protein with the mixed alpha/beta topology of PAS domains. GlbN had a stable apoprotein that was further stabilized and locally refolded by heme binding; in contrast, apoFixLH presented features of a molten globule. Sequence analyses (helicity, disorder, and polarity) and solvent accessibility calculations were performed to identify trends in the architecture of b hemoproteins. In several cases, the primary structure appeared biased toward a partially disordered binding pocket in the absence of the cofactor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Animals
  • Apoproteins / chemistry*
  • Apoproteins / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism
  • Bradyrhizobium / chemistry
  • Circular Dichroism
  • Cytochrome b Group / chemistry
  • Cytochrome b Group / metabolism
  • Globins / chemistry*
  • Globins / metabolism
  • Heme / chemistry*
  • Heme / metabolism
  • Hemeproteins / chemistry*
  • Hemeproteins / metabolism
  • Histidine Kinase
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Myoglobin / chemistry
  • Myoglobin / metabolism
  • Protein Binding
  • Protein Denaturation
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Thermodynamics


  • Apoproteins
  • Bacterial Proteins
  • Cytochrome b Group
  • Hemeproteins
  • Myoglobin
  • Heme
  • Globins
  • FixL protein, Bacteria
  • Histidine Kinase