Cellulose

, Volume 20, Issue 1, pp 115–125

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

Original Paper

DOI: 10.1007/s10570-012-9811-4

Cite this article as:
Kumar, G.N. & Srikumar, K. Cellulose (2013) 20: 115. doi:10.1007/s10570-012-9811-4

Abstract

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.

Keywords

Laccase Thermostability EPR Circular dichroism Thermal analysis 

Copyright information

© Springer Science+Business Media Dordrecht 2012

Authors and Affiliations

  1. 1.Department of Biochemistry and Molecular Biology, School of Life SciencesPondicherry UniversityPuducherryIndia

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