Influence of heme propionates on the nitrite reductase activity of myoglobin

Mary Grace I. Galinato, Aaron M. Trail, Olivia R. Steinbeck, Zhuoyan Si, Anthony M. Rodland, Jaclyn Gowen

Research output: Contribution to journalArticlepeer-review

Abstract

The heme propionates in myoglobin (Mb) form a H-bonding network among several residues within its second-sphere coordination, providing a key structural role towards Mb's functional properties. Our work aims to understand the role of the heme propionates on the nitrite reductase (NiR) activity (e.g. reduction of NO2 to NO) of this globin by studying an artificial dimethylester heme-substituted horse heart Mb (DME-Mb). The minor structural change brought about by esterification of the heme propionates causes the NiR rate to increase by more than over two-fold (5.6 ± 0.1 M−1 s−1) relative to wildtype (wt) Mb (2.3 ± 0.1 M−1 s−1). The lower pKa observed in DME-Mb may enhance the tendency of His64 towards protonation, therefore increasing the NiR rate. In addition, the nitrite binding constant (Knitrite) for DME-MbIII is greater than wt MbIII (350 M−1 versus 120 M−1). The disparity in the NiR activity correlates with the differences in electrostatic behavior, which influences the system's reactivity towards the approaching NO2 ion, and thus the formation of the FeII-NO2 intermediate.

Original languageEnglish (US)
Article number111630
JournalJournal of Inorganic Biochemistry
Volume226
DOIs
StatePublished - Jan 2022

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Inorganic Chemistry

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