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A pH-stable laccase from alkali-tolerant γ-proteobacterium JB: Purification, characterization and indigo carmine degradation

Paper ID Volume ID Publish Year Pages File Format Full-Text
18089 42711 2007 6 PDF Available
Title
A pH-stable laccase from alkali-tolerant γ-proteobacterium JB: Purification, characterization and indigo carmine degradation
Abstract

γ-Proteobacterium JB, an alkali-tolerant soil isolate, produced laccase constitutively in unbuffered medium. The enzyme was purified to homogeneity by ammonium sulphate precipitation, DEAE-sepharose anion exchange chromatography and preparatory polyacrylamide gel electrophoresis. The purified enzyme was a monomeric polypeptide (MW 120 kDa) and absorbed at 590 nm indicating the presence of Type I Cu2+-centre. It worked optimally at 55 °C and showed different pH optima for different substrates. The enzyme was highly stable in the pH range 4–10 even after 60 days at 4 °C. Km and Vmax values for syringaldazine, catechol, pyrogallol, p-phenylenediamine, l-methyl DOPA and guaiacol substrates were determined. Inhibitors, viz. azide, diethyldithiocarbamate, thioglycollate and cysteine-hydrochloride all inhibited laccase non-competitively using guaiacol as substrate at pH 6.5. The enzyme degraded indigo carmine (pH 9, 55 °C) to anthranilic acid via isatin as determined spectrophotometrically and by HPLC analysis. Degradation was enhanced in the presence of syringaldehyde (571%), vanillin (156%) and p-hydroxybenzoic acid (91.6%) but not HOBT.

Keywords
Laccase; pH-stable; γ-Proteobacterium; Indigo; Isatin; Degradation
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A pH-stable laccase from alkali-tolerant γ-proteobacterium JB: Purification, characterization and indigo carmine degradation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 41, Issues 6–7, 1 November 2007, Pages 794–799
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us