Carbon Monoxide Binding to Iron Porphyrins

The carbon monoxide affinities of iron complexes of meso-tetra ($\alpha $,$\alpha $,$\alpha $,$\alpha $-o-pivalamidophenyl)porphyrin (the ``picket fence'' porphyrin) and of a ``picket fence'' porphyrin derivative with an appended axial base have been measured in solution and comp...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 1979-12, Vol.76 (12), p.6035-6039
Main Authors: Collman, James P., Brauman, John I., Doxsee, Kenneth M.
Format: Article
Language:English
Subjects:
Animals
Biochemistry
Carbon monoxide
Carbon Monoxide - blood
Carbon Monoxide - metabolism
Heme - metabolism
Hemeproteins - metabolism
Hemoglobins
Henry law
Humans
Iron - metabolism
Ligands
Mathematical constants
Picket fences
Porphyrins
Porphyrins - metabolism
Solvation
Solvents
Structure-Activity Relationship
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Summary:The carbon monoxide affinities of iron complexes of meso-tetra ($\alpha $,$\alpha $,$\alpha $,$\alpha $-o-pivalamidophenyl)porphyrin (the ``picket fence'' porphyrin) and of a ``picket fence'' porphyrin derivative with an appended axial base have been measured in solution and compared with the CO affinities of various hemoproteins. The model complexes bind CO with much greater affinity than normal hemoproteins; the role of the steric bulk of distal residues in lowering the CO affinities of the hemoproteins is discussed. The significance of this lowered CO affinity is described with regard to endogenous CO. A discussion of mutant hemoglobins lacking distal residues that sterically inhibit the binding of CO is presented. The use of pressure units versus concentration units in equilibrium expressions is analyzed.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.76.12.6035