Role of C-terminal Acidic cluster in Stabilization of Heme spin State of ascorbate peroxidase from Leishmania major
IR@IICB: CSIR-Indian Institute of Chemical Biology, KolkataView Archive Info
Role of C-terminal Acidic cluster in Stabilization of Heme spin State of
ascorbate peroxidase from Leishmania major
Yadav, Rajesh K
Structural Biology & Bioinformatics
Architecture of hemoprotein is solely responsible for different nature of heme coordination. Here we
report that substitution of the acidic surface residue Glu226 to Ala in ascorbate peroxidase from Leishmania
major alters the 5 coordinate high spin (5cHS) to a 6 coordinate low spin (6cLS) form at pH 7.5.
Using UV–visible spectrophotometry, we show that the sixth ligand of heme in Glu226Ala at pH 7.5 is
hydroxo. When the pH is decreased to 5.5, a new species of Glu226Ala appeared that had a spectrum
characteristic of a 6cHS derivative. Stopped flow spectrophotometric techniques revealed that characteristics
of Compound I was not seen in the Glu226Ala in presence of H2O2. Similarly guaiacol, ascorbate and
ferrocytochrome c oxidation rate was 103 orders less for the Glu226Ala mutants compared to the wild
type. These data suggested that surface acidic residue Glu226 might play role in proper maintenance
of active site conformation.
Yadav, Rajesh K and Dolai, Subhankar and Pal, Swati and Adak, Subrata (2010) Role of C-terminal Acidic cluster in Stabilization of Heme spin State of ascorbate peroxidase from Leishmania major. Archives of Biochemistry and Biophysics, 495. pp. 129-135.