Lactoperoxidase-catalyzed oxidation of thiocyanate by hydrogen peroxide: sup 15 N nuclear magnetic resonance and optical spectral studies

Journal Article · Mon Dec 31 23:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00215a018· OSTI ID:5476472

Modi, S; Deodhar, S S; Behere, D V; Mitra, S ^[1]

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1. Tata Institute of Fundamental Research, Bombay (India)

To establish the agent(s) responsible for the activity of the lactoperoxidase (LPO)/SCN{sup {minus}}/H{sub 2}O{sub 2} system, the oxidation of thiocyanate with hydrogen peroxide, catalyzed by lactoperoxidase, has been studied by {sup 15}N NMR and optical spectroscopy at different concentrations of thiocyanate and hydrogen peroxide and at different pHs. The formation of hypothiocyanite ion (OSCN{sup {minus}}) as one of the oxidation products correlated well with activity of the LPO/SCN{sup {minus}}/H{sub 2}O{sub 2} system and was maximum when the concentrations of the H{sub 2}O{sub 2} and SCN{sup {minus}} were nearly the same and the pH was <6.0. At (H{sub 2}O{sub 2})/(SCN{sup {minus}}) = 1, OSCN{sup {minus}} decomposed very slowly back to thiocyanate. When the ratio (H{sub 2}O{sub 2})/(SCN{sup {minus}}) was above 2, formation of CN{sup {minus}} was observed, which was confirmed by {sup 15}N NMR and also by changes in the optical spectrum of LPO. The oxidation of thiocyanate by H{sub 2}O{sub 2} in the presence of LPO does not take place at pH >8.0. Since thiocyanate does not bind to LPO above this pH, the binding of thiocyanate to LPO is considered to be prerequisite for the oxidation of thiocyanate. Maximum inhibition of oxygen uptake by Streptococcus cremoris 972 bacteria was observed when hydrogen peroxide and thiocyanate were present in equimolar amounts and the pH was below 6.0.

• OSTI ID: 5476472
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 30:1; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ABSORPTION SPECTROSCOPY
ANTITHYROID DRUGS
CARBOHYDRATES
CARBONIC ACID DERIVATIVES
CHEMICAL REACTIONS
DISACCHARIDES
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ENZYME ACTIVITY
ENZYMES
HORMONE ANTAGONISTS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
ISOTOPES
LACTOSE
LIGHT NUCLEI
MAGNETIC RESONANCE
MEASURING INSTRUMENTS
NITROGEN 15
NITROGEN ISOTOPES
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
OLIGOSACCHARIDES
OPTICAL SPECTROMETERS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDATION
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PEROXIDASES
PEROXIDES
RESONANCE
SACCHARIDES
SPECTRA
SPECTROMETERS
SPECTROSCOPY
STABLE ISOTOPES
THIOCYANATES