Spectroscopical and functional characterization of the hemoglobin of Nostoc commune (UTEX 584 (Cyanobacterial)

Biochim Biophys Acta. 1996 Jan 4;1292(1):133-9. doi: 10.1016/0167-4838(95)00178-6.


Structural analysis of a monomeric hemoglobin from the cyanobacterium Nostoc commune strain UTEX 584, cyanoglobin (Potts et al. (1992) Science 256, 1690-1692), is presented. Cyanoglobin binds molecular oxygen reversibly, with high oxygen affinity and non-cooperativity. There was no evidence for decreased stability of the pigment at 37 degrees C. Cyanoglobin-specific antibodies showed no cross-reactivity with two reference hemoglobins, leghemoglobin a and sperm whale myoglobin. The absorption spectral properties of cyanoglobin differ significantly from those of the two reference hemoglobins. The spectrum of oxy-cyanoglobin most closely resembles that of an oxy-hemoglobin from the protozoan Tetrahymena pyriformis, a hemoprotein that shares substantial amino-acid sequence identity with cyanoglobin. Met-cyanoglobin possesses spectral characteristics at pH 7.0-9.0 that resemble those of the alkaline met-hemoglobin (a putative hemichrome) of another protozoan, Paramecium caudatum. The spin-state character of met-cyanoglobin is pH-dependent. Met-cyanoglobin does not coordinate the strong-field ligands, cyanide and azide, at pH 7.0. The capacity of cyanoglobin to coordinate cyanide increased with decreasing pH. Far-UV CD spectra of cyanoglobin are indicative of a protein with a significant amount of alpha-helical structure. Data from Soret-region CD spectra suggest that the orientations of the heme moieties in cyanoglobin and leghemoglobin a are similar to one another.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Blotting, Western
  • Circular Dichroism
  • Cyanobacteria / chemistry*
  • Escherichia coli / genetics
  • Heme / metabolism
  • Hemoglobins / chemistry*
  • Hemoglobins / genetics
  • Hemoglobins / isolation & purification
  • Hemoglobins / metabolism
  • Hydrogen-Ion Concentration
  • Leghemoglobin / chemistry
  • Leghemoglobin / immunology
  • Methemoglobin / chemistry
  • Myoglobin / immunology
  • Nitrogen Fixation
  • Oxygen / metabolism
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Spectrophotometry


  • Hemoglobins
  • Leghemoglobin
  • Myoglobin
  • Recombinant Proteins
  • cyanhemoglobin
  • Heme
  • Methemoglobin
  • Oxygen