Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance

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Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols : absolute rate constants and assessment of biological relevance. / Skaff, Ojia; Pattison, David I; Davies, Michael Jonathan.

In: Biochemical Journal, Vol. 422, No. 1, 15.08.2009, p. 111-7.

Research output: Contribution to journalJournal articleResearchpeer-review

Harvard

Skaff, O, Pattison, DI & Davies, MJ 2009, 'Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance', Biochemical Journal, vol. 422, no. 1, pp. 111-7. https://doi.org/10.1042/BJ20090276

APA

Skaff, O., Pattison, D. I., & Davies, M. J. (2009). Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance. Biochemical Journal, 422(1), 111-7. https://doi.org/10.1042/BJ20090276

Vancouver

Skaff O, Pattison DI, Davies MJ. Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance. Biochemical Journal. 2009 Aug 15;422(1):111-7. https://doi.org/10.1042/BJ20090276

Author

Skaff, Ojia ; Pattison, David I ; Davies, Michael Jonathan. / Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols : absolute rate constants and assessment of biological relevance. In: Biochemical Journal. 2009 ; Vol. 422, No. 1. pp. 111-7.

Bibtex

@article{b69ebddf820a489595374b76d9c55fab,
title = "Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols: absolute rate constants and assessment of biological relevance",
abstract = "MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by H(2)O(2) to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid, also know as cyanosulfenic acid) respectively. Specificity constants indicate that thiocyanate, SCN-, is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. Whereas HOCl and HOBr are powerful oxidizing agents, HOSCN appears to be a less reactive, but more thiol-specific oxidant. Although it is established that HOSCN selectively targets thiols, absolute kinetic data for the reactions of thiols with HOSCN are absent from the literature. This study shows for the first time that the reactions of HOSCN with low-molecular-mass thiol residues occur with rate constants in the range from 7.3 x 10(3) M(-1).s(-1) (for N-acetyl-cysteine at pH 7.4) to 7.7 x 10(6) M(-1).s(-1) (for 5-thio-2-nitrobenzoic acid at pH 6.0). An inverse relationship between the rate of reaction and the pKa of the thiol group was observed. The rates of reaction of HOSCN with thiol-containing proteins were also investigated for four proteins (creatine kinase, BSA, beta-lactoglobulin and beta-L-crystallins). The values obtained for cysteine residues on these proteins are in the range 1 x 10(4)- 7 x 10(4) M(-1).s(-1). These second-order rate constants indicate that HOSCN is a major mediator of thiol oxidation in biological systems exposed to peroxidase/H(2)O(2) systems at (patho)physiological concentrations of halide and SCN- ions, and that HOSCN may play an important role in inflammation-induced oxidative damage.",
keywords = "Animals, Cattle, Glutathione, Hydrogen-Ion Concentration, Kinetics, Molecular Weight, Nitrobenzoates, Proteins, Sulfhydryl Compounds, Thiocyanates",
author = "Ojia Skaff and Pattison, {David I} and Davies, {Michael Jonathan}",
year = "2009",
month = "8",
day = "15",
doi = "10.1042/BJ20090276",
language = "English",
volume = "422",
pages = "111--7",
journal = "Biochemical Journal",
issn = "0264-6021",
publisher = "Portland Press Ltd.",
number = "1",

}

RIS

TY - JOUR

T1 - Hypothiocyanous acid reactivity with low-molecular-mass and protein thiols

T2 - absolute rate constants and assessment of biological relevance

AU - Skaff, Ojia

AU - Pattison, David I

AU - Davies, Michael Jonathan

PY - 2009/8/15

Y1 - 2009/8/15

N2 - MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by H(2)O(2) to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid, also know as cyanosulfenic acid) respectively. Specificity constants indicate that thiocyanate, SCN-, is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. Whereas HOCl and HOBr are powerful oxidizing agents, HOSCN appears to be a less reactive, but more thiol-specific oxidant. Although it is established that HOSCN selectively targets thiols, absolute kinetic data for the reactions of thiols with HOSCN are absent from the literature. This study shows for the first time that the reactions of HOSCN with low-molecular-mass thiol residues occur with rate constants in the range from 7.3 x 10(3) M(-1).s(-1) (for N-acetyl-cysteine at pH 7.4) to 7.7 x 10(6) M(-1).s(-1) (for 5-thio-2-nitrobenzoic acid at pH 6.0). An inverse relationship between the rate of reaction and the pKa of the thiol group was observed. The rates of reaction of HOSCN with thiol-containing proteins were also investigated for four proteins (creatine kinase, BSA, beta-lactoglobulin and beta-L-crystallins). The values obtained for cysteine residues on these proteins are in the range 1 x 10(4)- 7 x 10(4) M(-1).s(-1). These second-order rate constants indicate that HOSCN is a major mediator of thiol oxidation in biological systems exposed to peroxidase/H(2)O(2) systems at (patho)physiological concentrations of halide and SCN- ions, and that HOSCN may play an important role in inflammation-induced oxidative damage.

AB - MPO (myeloperoxidase) catalyses the oxidation of chloride, bromide and thiocyanate by H(2)O(2) to HOCl (hypochlorous acid), HOBr (hypobromous acid) and HOSCN (hypothiocyanous acid, also know as cyanosulfenic acid) respectively. Specificity constants indicate that thiocyanate, SCN-, is a major substrate for MPO. HOSCN is also a major oxidant generated by other peroxidases including salivary, gastric and eosinophil peroxidases. Whereas HOCl and HOBr are powerful oxidizing agents, HOSCN appears to be a less reactive, but more thiol-specific oxidant. Although it is established that HOSCN selectively targets thiols, absolute kinetic data for the reactions of thiols with HOSCN are absent from the literature. This study shows for the first time that the reactions of HOSCN with low-molecular-mass thiol residues occur with rate constants in the range from 7.3 x 10(3) M(-1).s(-1) (for N-acetyl-cysteine at pH 7.4) to 7.7 x 10(6) M(-1).s(-1) (for 5-thio-2-nitrobenzoic acid at pH 6.0). An inverse relationship between the rate of reaction and the pKa of the thiol group was observed. The rates of reaction of HOSCN with thiol-containing proteins were also investigated for four proteins (creatine kinase, BSA, beta-lactoglobulin and beta-L-crystallins). The values obtained for cysteine residues on these proteins are in the range 1 x 10(4)- 7 x 10(4) M(-1).s(-1). These second-order rate constants indicate that HOSCN is a major mediator of thiol oxidation in biological systems exposed to peroxidase/H(2)O(2) systems at (patho)physiological concentrations of halide and SCN- ions, and that HOSCN may play an important role in inflammation-induced oxidative damage.

KW - Animals

KW - Cattle

KW - Glutathione

KW - Hydrogen-Ion Concentration

KW - Kinetics

KW - Molecular Weight

KW - Nitrobenzoates

KW - Proteins

KW - Sulfhydryl Compounds

KW - Thiocyanates

U2 - 10.1042/BJ20090276

DO - 10.1042/BJ20090276

M3 - Journal article

C2 - 19492988

VL - 422

SP - 111

EP - 117

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 1

ER -

ID: 129670348