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dc.contributor.authorChartchalerm Isarankura-Na-Ayudhyaen_US
dc.contributor.authorNatta Tansilaen_US
dc.contributor.authorApilak Worachartcheewanen_US
dc.contributor.authorLeif Bülowen_US
dc.contributor.authorVirapong Prachayasittikulen_US
dc.contributor.otherMahidol Universityen_US
dc.contributor.otherLunds Universiteten_US
dc.identifier.citationJournal of Microbiology and Biotechnology. Vol.20, No.3 (2010), 532-541en_US
dc.description.abstractPeroxidase-like activity of Vitreoscilla hemoglobin (VHb) has been recently disclosed. To maximize such activity, two catalytically conserved residues (histidine and arginine) found in the distal pocket of peroxidases have successfully been introduced into that of the VHb. A 15-fold increase in catalytic constant (kcat) was obtained in P54R variant, which was presumably attributable to the lower rigidity and higher hydrophilicity of the distal cavity arising from substitution of proline to arginine. None of the modifications altered the affinity towards either H2O2 or ABTS substrate. Spectroscopic studies revealed that VHb variants harboring the T29H mutation apparently demonstrated a spectral shift in both ferric and ferrous forms (406-408 to 411 nm, and 432 to 424-425 nm, respectively). All VHb proteins in the ferrous state had a λsoret peak at ~419 nm following the carbon monoxide (CO) binding. Expression of the P54R mutant mediated the downregulation of iron superoxide dismutase (FeSOD) as identified by two-dimensional gel electrophoresis (2-DE) and peptide mass fingerprinting (PMF). According to the high peroxidase activity of P54R, it could effectively eliminate autoxidation-derived H2O2, which is a cause of heme degradation and iron release. This decreased the iron availability and consequently reduced the formation of the Fe2+-ferric uptake regulator protein (Fe2+-Fur), an inducer of FeSOD expression.en_US
dc.rightsMahidol Universityen_US
dc.subjectBiochemistry, Genetics and Molecular Biologyen_US
dc.subjectImmunology and Microbiologyen_US
dc.titleBiochemical and cellular investigation of vitreoscilla hemoglobin (VHb) variants possessing efficient peroxidase activityen_US
Appears in Collections:Scopus 2006-2010

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