title: Electrochemical determination of heme-linked pKa values and the importance of using fluoride binding in heme proteins.
abstract: The ultraviolet-visible (UV-vis) spectroelectrochemical measurements of heme proteins in the presence of a heme-bound fluoride ion can be used as a probe for heme-linked ionizations of acid-base groups in the heme pocket. A detailed study of the pH dependence of the midpoint potential of skeletal horse myoglobin (Mb) with a heme-bound fluoride ion (Mb-F) reveals how protonation of the distal histidine (H64) changes the redox properties of the protein with a determined pKa of 5.3. In addition, fluoride binding in myoglobin provides a stabilization of -1.9 kcal/mol of the ferric Mb-F relative to ferric Mb without fluoride.
authors: Department of Chemistry, Saint Joseph's University, Philadelphia, PA 19131, USA. Electronic address: jcerda@sju.edu.
authors: Jose F
authors: JF
authors: Cerda
authors: Margaret H
authors: MH
authors: Roeder
authors: Danielle N
authors: DN
authors: Houchins
authors: Carmen X
authors: CX
authors: Guzman
authors: Emily J
authors: EJ
authors: Amendola
authors: Jacquelyn D
authors: JD
authors: Castorino
authors: Andrea L
authors: AL
authors: Fritz
mesh_terms: D000818:Animals; D001665:Binding Sites; D055664:Electrochemical Techniques; D004579:Electron Transport; D005459:Fluorides / Q000737:chemistry*; D006418:Heme / Q000032:analysis / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry*; D006736:Horses; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D018482:Muscle, Skeletal / Q000737:chemistry; D009211:Myoglobin / Q000032:analysis / Q000737:chemistry*; D010084:Oxidation-Reduction; D011485:Protein Binding; D011522:Protons; D013053:Spectrophotometry / Q000379:methods; D013816:Thermodynamics
chemical_list: D009211:Myoglobin; D011522:Protons; D006418:Heme; D006639:Histidine; D005459:Fluorides
keywords: Fluoride; Midpoint potential; Myoglobin; Spectroelectrochemistry