Insights Into How Heme Reduction Potentials Modulate Enzymatic Activities of a Myoglobin-based Functional Oxidase

Ambika Bhagi-Damodaran, Maximilian Kahle, Yelu Shi, Yong Zhang, Pia Ädelroth, Yi Lu

Research output: Contribution to journalArticlepeer-review

13 Scopus citations

Abstract

Heme-copper oxidase (HCO) is a class of respiratory enzymes that use a heme-copper center to catalyze O2 reduction to H2O. While heme reduction potential (E°′) of different HCO types has been found to vary >500 mV, its impact on HCO activity remains poorly understood. Here, we use a set of myoglobin-based functional HCO models to investigate the mechanism by which heme E°′ modulates oxidase activity. Rapid stopped-flow kinetic measurements show that increasing heme E°′ by ca. 210 mV results in increases in electron transfer (ET) rates by 30-fold, rate of O2 binding by 12-fold, O2 dissociation by 35-fold, while decreasing O2 affinity by 3-fold. Theoretical calculations reveal that E°′ modulation has significant implications on electronic charge of both heme iron and O2, resulting in increased O2 dissociation and reduced O2 affinity at high E°′ values. Overall, this work suggests that fine-tuning E°′ in HCOs and other heme enzymes can modulate their substrate affinity, ET rate and enzymatic activity.

Original languageEnglish (US)
Pages (from-to)6622-6626
Number of pages5
JournalAngewandte Chemie - International Edition
Volume56
Issue number23
DOIs
StatePublished - Jun 1 2017
Externally publishedYes

Bibliographical note

Funding Information:
This report is based on work supported by a grant from the US National Institute of Health (GM062211) to Y.L. and by a grant from the Faculty of Science at Stockholm University to P.?. Y.Z. acknowledges the partial support by an NSF grant CHE-1300912. A.B.-D. thanks the financial support from Schlumberger foundation Faculty for the Future fellowship.

Keywords

  • electron transfer
  • heme proteins
  • oxidoreductases
  • oxygen activation
  • redox chemistry

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