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Chromate reduction by cell-free extract of Bacillus firmus KUCr1

100%

Sau G. B., Chatterjee S., Mukherjee S. K.

Polish Journal of Microbiology

2010

tom 59

nr 3

Microbial enzymatic reduction of a toxic form of chromium [Cr(VI)] has been considered as an effective method for bioremediation of this metal. This study reports on the in vitro reduction of Cr(VI) using cell-free extracts from a Cr(VI) reducing Bacillusfirmus KUCr1 strain. Chromium reductase was found to be constitutive and its activity was observed both in soluble cell fractions (S₁₂and S₁₅₀) and membrane cell fraction (P₁₅₀). The reductase activity of S₁₂ fraction was found to be optimal at 40 μM Cr(VI) with enzyme concentration equivalent to 0.493 mg protein/ml. Enzyme activity was dependent on NADH or NADPH as electron donor; optimal temperature and pH for better enzyme activity were 70°C and 5.6, respectively. The Km value of the reductase was 58.33 μM chromate having a Vmax of 11.42 μM/min/mg protein. The metabolic inhibitor like sodium azide inhibited reductase activity of membrane fraction of the cell-free extract. Metal ions like Cu²⁺, Co²⁺, Ni²⁺ and As³⁺ stimulated the enzyme but others, such as Ag⁺, Hg²⁺, Zn²⁺, Mn²⁺, Cd²⁺ and Pb²⁺, inhibited Cr(VI) reductase activity.

The ability of new formamidine sugar-modified derivatives of daunorubicin to stimulate free radical formation in three enzymatic systems: NADH dehydrogenase, NADPH cytochrome p450 reductase and xanthine oxidase

80%

Pawlowska J., Tarasiuk J., Borowski E., Wasowska M., Oszczapowicz I., Wolf C. R.

Acta Biochimica Polonica

2000

tom 47

nr 1

Some sterically hindered N-substituted derivatives of daunorubicin are known to be poor substrates for NADH dehydrogenase, NADPH cytochrome P450 reductase and xanthine oxidase. In consequence, poor oxygen radical generation by these compounds is observed. In this study we examined a new family of sugar-N-substituted derivatives of daunorubicin bearing a bulky substituent introduced on the nitrogen atom through the amidine spacer. These compounds were found to be very active in radical formation catalyzed by all three studied enzymes. Thus, the introduction of a heterocyclic ring, even if it is bulky but flexible, on the nitrogen atom of daunosamine moiety through the one-atom spacer (amidine group), does not induce the steric hindrance effect on the interaction of daunorubicin derivatives with these flavoprotein enzymes.

Ograniczanie wyników

1 Acta Biochimica Polonica

1 Polish Journal of Microbiology

1 Borowski E.

1 Chatterjee S.

1 Mukherjee S. K.

1 Oszczapowicz I.

1 Pawlowska J.

1 Sau G. B.

1 Tarasiuk J.

1 Wasowska M.

1 Wolf C. R.

1 2010

1 2000

Wyniki wyszukiwania

Chromate reduction by cell-free extract of Bacillus firmus KUCr1

The ability of new formamidine sugar-modified derivatives of daunorubicin to stimulate free radical formation in three enzymatic systems: NADH dehydrogenase, NADPH cytochrome p450 reductase and xanthine oxidase