Peroxidatic activity of catalase

Mordechai L. Kremer

doi:10.1016/0005-2744(70)90052-5

Peroxidatic activity of catalase

Mordechai L. Kremer^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

50 Scopus citations

Abstract

1. 1. The oxidation of ethanol by a mixture of H₂O₂ and catalase has been studied. By using a 1.10⁶-fold excess of ethanol (H₂A) over H₂O₂, the competition between ethanol and H₂O₂ for the active enzyme-substrate complex (C_I) has been demonstrated. 2. 2. Under conditions where ethanol competes for C_I, the overall second-order rate constant (k_H) becomes a function of the ratio of the concentrations of ethanol and H₂O₂ (R). An increase of R causes a decrease of k_H. 3. 3. From the dependence of k_H on R the individual rate constants of the peroxidatic mechanism of catalase action have been calculated. E + H₂O₂ → IC_I k₁ = (5.6 ± 0.5) · IO⁶M^-1 · sec^-1 C_I + H₂O₂ → 4E + O₂ + 2 H₂O k₄ = (I.2 ± 0.I) · IO⁷M^-1 · sec^-1 C_I + H₂A → 5E + A + 2 H₂O k₅ = (I.8 ± 0.4) · IO²M^-1 · sec^-1 4. 4. From these results a steady-state saturation of 30% of catalase hematins by H₂O₂ during the catalatic reaction has been calculated.

Original language	English
Pages (from-to)	199-209
Number of pages	11
Journal	BBA - Enzymology
Volume	198
Issue number	2
DOIs	https://doi.org/10.1016/0005-2744(70)90052-5
State	Published - 11 Feb 1970
Externally published	Yes

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title = "Peroxidatic activity of catalase",

abstract = "1. 1. The oxidation of ethanol by a mixture of H2O2 and catalase has been studied. By using a 1.106-fold excess of ethanol (H2A) over H2O2, the competition between ethanol and H2O2 for the active enzyme-substrate complex (CI) has been demonstrated. 2. 2. Under conditions where ethanol competes for CI, the overall second-order rate constant (kH) becomes a function of the ratio of the concentrations of ethanol and H2O2 (R). An increase of R causes a decrease of kH. 3. 3. From the dependence of kH on R the individual rate constants of the peroxidatic mechanism of catalase action have been calculated. E + H2O2 → ICI k1 = (5.6 ± 0.5) · IO6M-1 · sec-1 CI + H2O2 → 4E + O2 + 2 H2O k4 = (I.2 ± 0.I) · IO7M-1 · sec-1 CI + H2A → 5E + A + 2 H2O k5 = (I.8 ± 0.4) · IO2M-1 · sec-1 4. 4. From these results a steady-state saturation of 30% of catalase hematins by H2O2 during the catalatic reaction has been calculated.",

author = "Kremer, {Mordechai L.}",

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doi = "10.1016/0005-2744(70)90052-5",

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N2 - 1. 1. The oxidation of ethanol by a mixture of H2O2 and catalase has been studied. By using a 1.106-fold excess of ethanol (H2A) over H2O2, the competition between ethanol and H2O2 for the active enzyme-substrate complex (CI) has been demonstrated. 2. 2. Under conditions where ethanol competes for CI, the overall second-order rate constant (kH) becomes a function of the ratio of the concentrations of ethanol and H2O2 (R). An increase of R causes a decrease of kH. 3. 3. From the dependence of kH on R the individual rate constants of the peroxidatic mechanism of catalase action have been calculated. E + H2O2 → ICI k1 = (5.6 ± 0.5) · IO6M-1 · sec-1 CI + H2O2 → 4E + O2 + 2 H2O k4 = (I.2 ± 0.I) · IO7M-1 · sec-1 CI + H2A → 5E + A + 2 H2O k5 = (I.8 ± 0.4) · IO2M-1 · sec-1 4. 4. From these results a steady-state saturation of 30% of catalase hematins by H2O2 during the catalatic reaction has been calculated.

AB - 1. 1. The oxidation of ethanol by a mixture of H2O2 and catalase has been studied. By using a 1.106-fold excess of ethanol (H2A) over H2O2, the competition between ethanol and H2O2 for the active enzyme-substrate complex (CI) has been demonstrated. 2. 2. Under conditions where ethanol competes for CI, the overall second-order rate constant (kH) becomes a function of the ratio of the concentrations of ethanol and H2O2 (R). An increase of R causes a decrease of kH. 3. 3. From the dependence of kH on R the individual rate constants of the peroxidatic mechanism of catalase action have been calculated. E + H2O2 → ICI k1 = (5.6 ± 0.5) · IO6M-1 · sec-1 CI + H2O2 → 4E + O2 + 2 H2O k4 = (I.2 ± 0.I) · IO7M-1 · sec-1 CI + H2A → 5E + A + 2 H2O k5 = (I.8 ± 0.4) · IO2M-1 · sec-1 4. 4. From these results a steady-state saturation of 30% of catalase hematins by H2O2 during the catalatic reaction has been calculated.

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Peroxidatic activity of catalase

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