The ultra-violet visible (UV/Vis) absorption spectrum of laccase was similar to that observed of other fungal laccases (Coll et al. 1993; Eggert et al. 1996) with a Type I band at 614 nm, corresponding to the blue copper of laccases (Reinhammer and Malstrom 1981) and a broad band at 330 nm indicative of a Type III binuclear copper center (Malkin et al. 1969; Reinhammer 1984). The EPR spectrum of purified laccase had two superimposed signals of Type I and Type II copper centers.

The laccase was stable at 60°C for1 h and still retained much activity after 2 h incubation at 80°C. It differed from the laccase of P. cinnabarinus PB (Eggert et al. 1996) which was inactivated after incubation at 80°C for 1 h. The enzyme was still active in bioreactors run at 37°C for 25 days but lost activity on prolonged treatment at the higher temperatures.

The pH optimum for syringaldazine was between pH 4.4 and 5 and for guaiacol between pH 4 and 4.5. The Km was

0.03 mM for syringaldazine and 0.33 mM guaiacol. Activity was irreversibly inhibited by 0.1 mM sodium azide and by ascorbic acid at 1 mM.

Was this article helpful?

0 0
Growing Soilless

Growing Soilless

This is an easy-to-follow, step-by-step guide to growing organic, healthy vegetable, herbs and house plants without soil. Clearly illustrated with black and white line drawings, the book covers every aspect of home hydroponic gardening.

Get My Free Ebook

Post a comment