1H nmr studies of complexes of ferric leghemoglobin with substituted pyridines and nicotinic acids

Bridget C. Mabbutt*, Peter E. Wright

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

The 1H nuclear magnetic resonance (nmr) spectra of complexes of soybean ferric leghemoglobin with 3-substituted pyridines and 5-substituted nicotinic acids have been recorded in order to determine the influence of axial ligands on heme electronic structure. The hyperfine shifted resonances of the heme group were assigned by analogy to previous assignments for the pyridine and nicotinic acid complexes of leghemoglobin. The spectra are characteristic of predominantly low-spin ferric heme complexes. For the pyridine complexes, the rate of ligand exchange was found to increase with decreasing ligand pKA. For many of the complexes, optical and nmr spectra reveal the presence of an equilibrium mixture of high- and low-spin states of the iron atom. The percentage of high-spin component increases with decreasing ligand pKA Smaller hyperfine shifts are noted for leghemoglobin complexes with ligands capable of weak ligand → metal π bonding. The pattern of hyperfine shifted resonances is similar for all complexes studied and indicates that the overall heme electronic structure is dominated by the bonding to the proximal histidine.

Original languageEnglish
Pages (from-to)123-132
Number of pages10
JournalJournal of Inorganic Biochemistry
Volume18
Issue number2
DOIs
Publication statusPublished - 1983
Externally publishedYes

Fingerprint Dive into the research topics of '<sup>1</sup>H nmr studies of complexes of ferric leghemoglobin with substituted pyridines and nicotinic acids'. Together they form a unique fingerprint.

Cite this