Setting an Upper Limit on the Myoglobin Iron(IV)Hydroxide pKa: Insight into Axial Ligand Tuning in Heme Protein Catalysis | Zendy

Timothy H. Yosca | Zendy; Rachel K. Behan | Zendy; Courtney M. Krest | Zendy; Elizabeth L. Onderko | Zendy; Matthew Langston | Zendy; Michael T. Green | Zendy

Open Access

Setting an Upper Limit on the Myoglobin Iron(IV)Hydroxide pK_a: Insight into Axial Ligand Tuning in Heme Protein Catalysis

Author(s) -

Timothy H. Yosca,

Rachel K. Behan,

Courtney M. Krest,

Elizabeth L. Onderko,

Matthew Langston,

Michael T. Green

Publication year - 2014

Publication title -

journal of the american chemical society

Language(s) - English

Resource type - Journals

SCImago Journal Rank - 7.115

H-Index - 612

eISSN - 1520-5126

pISSN - 0002-7863

DOI - 10.1021/ja503588n

Subject(s) - chemistry , myoglobin , heme , histidine , ligand (biochemistry) , hydroxide , hemeprotein , protonation , catalysis , inorganic chemistry , organic chemistry , enzyme , biochemistry , ion , receptor

To provide insight into the iron(IV)hydroxide pK(a) of histidine ligated heme proteins, we have probed the active site of myoglobin compound II over the pH range of 3.9-9.5, using EXAFS, Mössbauer, and resonance Raman spectroscopies. We find no indication of ferryl protonation over this pH range, allowing us to set an upper limit of 2.7 on the iron(IV)hydroxide pK(a) in myoglobin. Together with the recent determination of an iron(IV)hydroxide pK(a) ∼ 12 in the thiolate-ligated heme enzyme cytochrome P450, this result provides insight into Nature's ability to tune catalytic function through its choice of axial ligand.

The content you want is available to Zendy users.

Already have an account? Click here to sign in.

Having issues? You can contact us here

Accelerating Research