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1999 | 46 | 4 | 919-927
Article title

Kinetic studies on the oxidation of nitrite by horseradish peroxidase and lactoperoxidase

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EN
Abstracts
EN
The reaction of nitrite (NO-_2) with horseradish peroxidase and lactoperoxidase was studied. Sequential mixing sopped-flow measeruments gave the following values for the rate constants of the reaction of nitrite with compounds II (oxoferryl heme intermediates) of horseradish peroxidase and lactoperoxidase at pH 7.0, 13.3 ± 0.07 mol^{-1}dm^3s^{-1} and 3.5 ± 0.05 · 10^4mol^{-1}dm^3s^{-1}, respectively. Nitrite, at neutral pH, influenced measurements of activity of lactoperoxidase with typical substrates like 2,2'-azino-bis[ethyl-benzothiazoline-(6)-sulphonic acid] (ABTS), guaiacol or thiocyanate (SCN-). The rate of ABTS and guaiacol oxidation increased linearly with nitrite concentration up to 2.5-5 mmol dm^{-3}. On the other hand, two-electron SCN- oxidation was inhibited in the presence od nitrite. Thus, nitrite competed with the investigated substrates of lactoperoxidase. The intermediate, most probably nitrogen dioxide (*NO_2), reacted more rapidly with ABTS or guaiacol than did lactoperoxidase compound II. It did not, however, effectively oxidize SCN- to OSCN-. NO-_2 did not influence the activity measurements of horseradish peroxidase by ABTS or guaiacol method.
Publisher

Year
Volume
46
Issue
4
Pages
919-927
Physical description
Dates
published
1999
received
1999-10-14
Contributors
  • Institute of Applied Radiation Chemistry, Technical University of Łódź, W. Wróblewskiego 15, 93-950 Łódź
References
Document Type
Publication order reference
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YADDA identifier
bwmeta1.element.bwnjournal-article-abpv46i4p919kz
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