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Comparison of substrate specificity of tyrosinases from Trichoderma reesei and Agaricus bisporus

Paper ID Volume ID Publish Year Pages File Format Full-Text
17851 42701 2009 10 PDF Available
Title
Comparison of substrate specificity of tyrosinases from Trichoderma reesei and Agaricus bisporus
Abstract

Understanding the substrate specificity of tyrosinases (EC 1.14.18.1) as well as their capability to oxidize peptide-bound tyrosine residues is important in a view of applicability of tyrosinases. In the present study, two fungal tyrosinases, an extracellular enzyme from the filamentous fungus Trichoderma reesei (TrT) and an intracellular enzyme from the edible mushroom Agaricus bisporus (AbT) were compared. Oxidation of various mono- and diphenolic compounds and tyrosine-containing tripeptides was examined and kinetic constants determined using spectrophotometric and oxygen consumption measurements. TrT and AbT were found to show notable differences in their substrate specificity. TrT generally showed 10-fold higher Km values than AbT. The presence of a carboxylic and amine group in the substrate influenced the enzymes differently. While the substrates with a carboxyl group were observed not to be effectively oxidized by AbT, the amine group seemed to hider the oxidation in the TrT-catalyzed reactions. Moreover, the UV–visible absorption spectra on the oxidation of catechol and hydrocaffeic acid showed that the product patterns were different between the enzymes. The result is interesting as the primary products from tyrosinase-catalyzed reactions were assumed to be identical with both enzymes. Furthermore, a nucleophilic 3-methyl-2-benzothiazolinone hydrazone (MBTH) affected differently on the activity of the tyrosinases: the lag period related to the oxidation of monophenols was prolonged by MBTH with TrT, whereas with AbT the lag was shortened.

Keywords
TrT, tyrosinase from Trichoderma reesei; AbT, tyrosinase from Agaricus bisporus; Y, tyrosine; G, glycine; MBTH, 3-methyl-2-benzothiazolinone hydrazone; [S], substrate concentrationTyrosinase; Fungal; Substrate specificity; Kinetic constants
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Comparison of substrate specificity of tyrosinases from Trichoderma reesei and Agaricus bisporus
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Publisher
Database: Elsevier - ScienceDirect
Journal: Enzyme and Microbial Technology - Volume 44, Issue 1, 6 January 2009, Pages 1–10
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