title: Characterization of xerophytic thermophilic laccase exhibiting metal ion-dependent dye decolorization potential.
abstract: Five laccase enzyme isoforms were isolated and purified to homogeneity from the cladodes of xerophytic Cereus pterogonus and Opuntia vulgaris plant species. Catalytic activity of all isoforms was enhanced 40 % by 1 mM Cu(2+) and 1 mM Mn(2+), whereas the activity was inhibited 100 % by 10 mM Fe(2+). Enzyme was found stable in 4 M urea and exhibited inactivity of 50 % in 8 M urea concentration. Ethylenediaminetetraacetic acid and cysteine-HCl were able to completely inhibit the enzyme activity at 1 mM and 100 μM, respectively. Preheated enzyme samples showed enhanced and stable catalytic activity in the presence of divalent cations over a period of 30 min compared with controls. In the presence of metal ions (1 mM Cu(2+) and 1 mM Mn(2+)), the preheated enzyme forms (60-90 °C) achieved 97 % of Malachite green and 98.75 % of Indigo blue (both at 2 %, w/v) dye decolorization in 12 h.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Life Sciences, Pondicherry University, Puducherry, India 605014.
authors.forename: Gali Nirmal
authors.initials: GN
authors.lastname: Kumar
authors.forename: Kotteazeth
authors.initials: K
authors.lastname: Srikumar
mesh_terms: D029421:Cactaceae / Q000201:enzymology* / Q000502:physiology*; D003116:Color; D004396:Coloring Agents / Q000302:isolation & purification / Q000378:metabolism*; D004795:Enzyme Stability; D007220:Industrial Waste; D007700:Kinetics; D042845:Laccase / Q000737:chemistry / Q000378:metabolism*; D008670:Metals / Q000737:chemistry / Q000494:pharmacology*; D011489:Protein Denaturation / Q000187:drug effects; D013696:Temperature; D013997:Time Factors
chemical_list: D004396:Coloring Agents; D007220:Industrial Waste; D008670:Metals; D042845:Laccase