Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase

Z. S. Farhangrazi, R. Sinclair, Linda S Powers, I. Yamazaki

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Horseradish peroxidase (HRP) was oxidized by IrCl62- to a mixture of compounds I and II, the rate of oxidation and the ratio of the mixture being greatly affected by pH (Hayashi & Yamazaki, 1979). Oxidation of HRP by IrCl62- in the presence of fluoride was significantly accelerated. This resulted in the formation of a new compound which is a ferric fluoride complex containing a porphyrin π-cation radical. The spectrum of the new compound showed a decreased absorption band in the Soret region and a broad band at 570 nm; which was converted to that of the original ferric fluoride complex by addition of ascorbate or hydroquinone. Addition of cyanide slowed down the oxidation of HRP by IrCl62-, and the oxidation product was the same as that obtained in the absence of cyanide. Compound I was formed when H2O2 was added to HRP in the presence of fluoride or cyanide. The one-electron reduction potential (Eo′) of the oxidized HRP-fluoride complex was measured at several pH values, the Eo′ value at pH 7 being 861 ± 4 mV. The ratio of ΔEo′ to ΔpH was 49 mV/pH unit.

Original languageEnglish (US)
Pages (from-to)14970-14974
Number of pages5
JournalBiochemistry
Volume34
Issue number46
StatePublished - 1995
Externally publishedYes

Fingerprint

Porphyrins
Horseradish Peroxidase
Fluorides
Cations
Cyanides
Oxidation
Absorption spectra
Electrons
ferric fluoride

ASJC Scopus subject areas

  • Biochemistry

Cite this

Farhangrazi, Z. S., Sinclair, R., Powers, L. S., & Yamazaki, I. (1995). Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase. Biochemistry, 34(46), 14970-14974.

Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase. / Farhangrazi, Z. S.; Sinclair, R.; Powers, Linda S; Yamazaki, I.

In: Biochemistry, Vol. 34, No. 46, 1995, p. 14970-14974.

Research output: Contribution to journalArticle

Farhangrazi, ZS, Sinclair, R, Powers, LS & Yamazaki, I 1995, 'Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase', Biochemistry, vol. 34, no. 46, pp. 14970-14974.
Farhangrazi, Z. S. ; Sinclair, R. ; Powers, Linda S ; Yamazaki, I. / Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase. In: Biochemistry. 1995 ; Vol. 34, No. 46. pp. 14970-14974.
@article{ccb5f69222a145adaaa0d406415e388a,
title = "Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase",
abstract = "Horseradish peroxidase (HRP) was oxidized by IrCl62- to a mixture of compounds I and II, the rate of oxidation and the ratio of the mixture being greatly affected by pH (Hayashi & Yamazaki, 1979). Oxidation of HRP by IrCl62- in the presence of fluoride was significantly accelerated. This resulted in the formation of a new compound which is a ferric fluoride complex containing a porphyrin π-cation radical. The spectrum of the new compound showed a decreased absorption band in the Soret region and a broad band at 570 nm; which was converted to that of the original ferric fluoride complex by addition of ascorbate or hydroquinone. Addition of cyanide slowed down the oxidation of HRP by IrCl62-, and the oxidation product was the same as that obtained in the absence of cyanide. Compound I was formed when H2O2 was added to HRP in the presence of fluoride or cyanide. The one-electron reduction potential (Eo′) of the oxidized HRP-fluoride complex was measured at several pH values, the Eo′ value at pH 7 being 861 ± 4 mV. The ratio of ΔEo′ to ΔpH was 49 mV/pH unit.",
author = "Farhangrazi, {Z. S.} and R. Sinclair and Powers, {Linda S} and I. Yamazaki",
year = "1995",
language = "English (US)",
volume = "34",
pages = "14970--14974",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "46",

}

TY - JOUR

T1 - Formation of a porphyrin π-cation radical in the fluoride complex of horseradish peroxidase

AU - Farhangrazi, Z. S.

AU - Sinclair, R.

AU - Powers, Linda S

AU - Yamazaki, I.

PY - 1995

Y1 - 1995

N2 - Horseradish peroxidase (HRP) was oxidized by IrCl62- to a mixture of compounds I and II, the rate of oxidation and the ratio of the mixture being greatly affected by pH (Hayashi & Yamazaki, 1979). Oxidation of HRP by IrCl62- in the presence of fluoride was significantly accelerated. This resulted in the formation of a new compound which is a ferric fluoride complex containing a porphyrin π-cation radical. The spectrum of the new compound showed a decreased absorption band in the Soret region and a broad band at 570 nm; which was converted to that of the original ferric fluoride complex by addition of ascorbate or hydroquinone. Addition of cyanide slowed down the oxidation of HRP by IrCl62-, and the oxidation product was the same as that obtained in the absence of cyanide. Compound I was formed when H2O2 was added to HRP in the presence of fluoride or cyanide. The one-electron reduction potential (Eo′) of the oxidized HRP-fluoride complex was measured at several pH values, the Eo′ value at pH 7 being 861 ± 4 mV. The ratio of ΔEo′ to ΔpH was 49 mV/pH unit.

AB - Horseradish peroxidase (HRP) was oxidized by IrCl62- to a mixture of compounds I and II, the rate of oxidation and the ratio of the mixture being greatly affected by pH (Hayashi & Yamazaki, 1979). Oxidation of HRP by IrCl62- in the presence of fluoride was significantly accelerated. This resulted in the formation of a new compound which is a ferric fluoride complex containing a porphyrin π-cation radical. The spectrum of the new compound showed a decreased absorption band in the Soret region and a broad band at 570 nm; which was converted to that of the original ferric fluoride complex by addition of ascorbate or hydroquinone. Addition of cyanide slowed down the oxidation of HRP by IrCl62-, and the oxidation product was the same as that obtained in the absence of cyanide. Compound I was formed when H2O2 was added to HRP in the presence of fluoride or cyanide. The one-electron reduction potential (Eo′) of the oxidized HRP-fluoride complex was measured at several pH values, the Eo′ value at pH 7 being 861 ± 4 mV. The ratio of ΔEo′ to ΔpH was 49 mV/pH unit.

UR - http://www.scopus.com/inward/record.url?scp=0028972055&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0028972055&partnerID=8YFLogxK

M3 - Article

C2 - 7578110

AN - SCOPUS:0028972055

VL - 34

SP - 14970

EP - 14974

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 46

ER -