PMID: 44192Dec 1, 1979

A re-evaluation of some basic structural and functional properties of Pseudomonas cytochrome oxidase

The Biochemical Journal
M C SilvestriniC Greenwood

Abstract

Determinations of iron content and dry-weight measurements on samples of Pseudomonas cytochrome oxidase were coupled with sodium dodecyl sulphate/polyacrylamide-gel-electrophoresis studies of both the native protein and covalently cross-linked oligomers in order to estimate the enzyme's molecular weight and spectral absorption coefficients. A value of epsilon(ox.) (410)=282x10(3) litre.mol(-1).cm(-1) was calculated for a dimeric protein molecule having a total molecular weight of 122000 (based on iron analysis). Steady-state kinetic observations of the enzyme-catalysed oxidation of reduced azurin by nitrite indicated a marked increase in enzyme inactivation as the pH was raised from 5.7 to 7.2. Since NO, a product of the nitrite reductase activity of Pseudomonas cytochrome oxidase, is known to bind to the enzyme, a study was undertaken to try to assess the potential of NO as a product inhibitor. Investigations showed that samples of the oxidized protein at pH values 4, 5 and 6 bound NO to both haem c and d(1) components, but oxidized enzyme samples at pH7 and above formed their reduced ligand-bound forms when placed under an atmosphere of the gas. Ascorbate-reduced enzyme samples at pH4, 5, 6 and 7 were also found to bind NO at...Continue Reading

References

May 18, 1999·The Journal of Biological Chemistry·D NurizzoM Tegoni
Feb 28, 2001·Proceedings of the National Academy of Sciences of the United States of America·F CutruzzolàM Brunori

Related Concepts

Cytochrome c Oxidase Subunit VIa
Nitrite Reductase (NO-forming) Activity
Nitrite Reductase
Azurin
Azurin Activity
Ascorbate
Oxidation
Dimethyl Suberimidate
Pseudomonas aeruginosa
Nitrite Measurement

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