Kinetics of Calcium Release from Manganese Peroxidase during Thermal Inactivation

Timofeevski, Serguei L.; Aust, Steven D.

doi:10.1006/abbi.1997.0104

Cited by 14 publications

(6 citation statements)

References 27 publications

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“…On the other hand, the spectrum at neutral pH was characteristic of a VP with an hexacoordinated low-spin heme-iron [ 53 ]. According to previous studies, this form of the enzyme is the result of the formation of a bis-histidyl heme iron complex, in which both proximal and distal histidines are involved, due to loss of one or the two structural Ca 2+ ions upon thermal [ 54 , 55 ] or alkaline [ 56 , 57 ] inactivation. An exhaustive characterization of a Ca 2+ -depleted VP has been reported revealing that, although it can be activated by H 2 O 2 , its redox potential and catalytic activity are dramatically affected [ 53 ].…”

Section: Discussionmentioning

confidence: 99%

Improving the pH-stability of Versatile Peroxidase by Comparative Structural Analysis with a Naturally-Stable Manganese Peroxidase

et al. 2015

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Versatile peroxidase (VP) from the white-rot fungus Pleurotus eryngii is a high redox potential peroxidase of biotechnological interest able to oxidize a wide range of recalcitrant substrates including lignin, phenolic and non-phenolic aromatic compounds and dyes. However, the relatively low stability towards pH of this and other fungal peroxidases is a drawback for their industrial application. A strategy based on the comparative analysis of the crystal structures of VP and the highly pH-stable manganese peroxidase (MnP4) from Pleurotus ostreatus was followed to improve the VP pH stability. Several interactions, including hydrogen bonds and salt bridges, and charged residues exposed to the solvent were identified as putatively contributing to the pH stability of MnP4. The eight amino acid residues responsible for these interactions and seven surface basic residues were introduced into VP by directed mutagenesis. Furthermore, two cysteines were also included to explore the effect of an extra disulfide bond stabilizing the distal Ca2+ region. Three of the four designed variants were crystallized and new interactions were confirmed, being correlated with the observed improvement in pH stability. The extra hydrogen bonds and salt bridges stabilized the heme pocket at acidic and neutral pH as revealed by UV-visible spectroscopy. They led to a VP variant that retained a significant percentage of the initial activity at both pH 3.5 (61% after 24 h) and pH 7 (55% after 120 h) compared with the native enzyme, which was almost completely inactivated. The introduction of extra solvent-exposed basic residues and an additional disulfide bond into the above variant further improved the stability at acidic pH (85% residual activity at pH 3.5 after 24 h when introduced separately, and 64% at pH 3 when introduced together). The analysis of the results provides a rational explanation to the pH stability improvement achieved.

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Section: Discussionmentioning

confidence: 99%

Improving the pH-stability of Versatile Peroxidase by Comparative Structural Analysis with a Naturally-Stable Manganese Peroxidase

et al. 2015

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“…The low stability is reported as a common property of MnP enzymes (Sutherland and Aust 1996;Timofeevski and Aust 1997).…”

Section: Treatment Of Dye Containing Wastewater By P Ostreatus Laccasesmentioning

confidence: 98%

Bio-remediation of colored industrial wastewaters by the white-rot fungi Phanerochaete chrysosporium and Pleurotus ostreatus and their enzymes

et al. 2008

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The effect of Phanerochaete chrysosporium and Pleurotus ostreatus whole cells and their ligninolytic enzymes on models of colored industrial wastewaters was evaluated. Models of acid, direct and reactive dye wastewaters from textile industry have been defined on the basis of discharged amounts, economic relevance and representativeness of chemical structures of the contained dyes. Phanerochaete chrysosporium provided an effective decolourization of direct dye wastewater model, reaching about 45% decolourization in only 1 day of treatment, and about 90% decolourization within 7 days, whilst P. ostreatus was able to decolorize and detoxify acid dye wastewater model providing 40% decolourization in only 1 day, and 60% in 7 days. P. ostreatus growth conditions that induce laccase production (up to 130,000 U/l) were identified, and extra-cellular enzyme mixtures, with known laccase isoenzyme composition, were produced and used in wastewater models decolourization. The mixtures decolorized and detoxified the acid dye wastewater model, suggesting laccases as the main agents of wastewater decolourization by P. ostreatus. A laccase mixture was immobilized by entrapment in Cu-alginate beads, and the immobilized enzymes were shown to be effective in batch decolourization, even after 15 stepwise additions of dye for a total exposure of about 1 month.

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“…Site-directed mutations at F190 and D242 of MnP indicate they influence the electronic environment around the heme Whitwam et al 1999). Calcium also plays a role in maintaining the heme environment critical for catalysis Aust 1996, 1997;Timofeevski and Aust 1997).…”

Section: Manganese Peroxidasementioning

confidence: 99%

Enzymology and Molecular Biology of Lignin Degradation

Cullen

Kersten

1996

Biochemistry and Molecular Biology

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Kinetics of Calcium Release from Manganese Peroxidase during Thermal Inactivation

Cited by 14 publications

References 27 publications

Improving the pH-stability of Versatile Peroxidase by Comparative Structural Analysis with a Naturally-Stable Manganese Peroxidase

Improving the pH-stability of Versatile Peroxidase by Comparative Structural Analysis with a Naturally-Stable Manganese Peroxidase

Bio-remediation of colored industrial wastewaters by the white-rot fungi Phanerochaete chrysosporium and Pleurotus ostreatus and their enzymes

Enzymology and Molecular Biology of Lignin Degradation

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