Biophysical characterization of thermophilic laccase from the xerophytes : Cereus pterogonus and Opuntia vulgaris

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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  • Gali Nirmal Kumar
  • Kotteazeth Srikumar

Related Research Unit(s)


Original languageEnglish
Pages (from-to)115-125
Journal / PublicationCellulose
Issue number1
Online published1 Feb 2013
Publication statusPublished - Feb 2013


Biophysical characterization of laccase enzyme isoforms from two different xerophytic plants Cereus pterogonus and Opuntia vulgaris was carried out using EPR, fluorescence and circular dichroism (CD) spectroscopy while their thermal denaturation profiles were investigated employing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). EPR analysis revealed the presence of endogenous copper. The hyperfine splitting of EPR spectrum reduced with increase in the complexity of enzyme protein. Raise in temperature did not alter the protein fluorescence emission suggestive of high temperature stability of the enzyme, causing the tryptophan and tyrosine residues to remain buried within the protein structure. Far-UV CD spectrum revealed existence of 60 % random coils in enzyme structure even at elevated temperatures and in presence of metal ions and protein denaturants. DSC analysis provided a Tm in the range 95-121 °C for the native and 158-199 °C for the metal associated laccase isoforms. Loss in weight of the enzyme protein by 10-18 % was noted up to 100 °C when determined through TGA. The thermostable plant xerophytic laccase enzyme isoforms will be of potential use in textile, dyeing, pulping and biotechnology applications.

Research Area(s)

  • Circular dichroism, EPR, Laccase, Thermal analysis, Thermostability