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Please use this identifier to cite or link to this item: http://repository.li.mahidol.ac.th/dspace/handle/123456789/28770
Title: Biochemical and cellular investigation of vitreoscilla hemoglobin (VHb) variants possessing efficient peroxidase activity
Authors: Chartchalerm Isarankura-Na-Ayudhya
Natta Tansila
Apilak Worachartcheewan
Leif Bülow
Virapong Prachayasittikul
Mahidol University
Lunds Universitet
Keywords: Biochemistry, Genetics and Molecular Biology;Immunology and Microbiology
Issue Date: 1-Mar-2010
Citation: Journal of Microbiology and Biotechnology. Vol.20, No.3 (2010), 532-541
Abstract: Peroxidase-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.
URI: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=77954279964&origin=inward
http://repository.li.mahidol.ac.th/dspace/handle/123456789/28770
ISSN: 17388872
10177825
Appears in Collections:Scopus 2006-2010

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