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Comparison of the characteristics of fungal and plant tyrosinases

Paper ID Volume ID Publish Year Pages File Format Full-Text
25202 43559 2007 10 PDF Available
Title
Comparison of the characteristics of fungal and plant tyrosinases
Abstract

Enzymatic crosslinking provides valuable means for modifying functionality and structural properties of different polymers. Tyrosinases catalyze the hydroxylation of various monophenols to the corresponding o-diphenols, and the subsequent oxidation of o-diphenols to the corresponding quinones, which are highly reactive and can further undergo non-enzymatic reactions to produce mixed melanins and heterogeneous polymers. Tyrosinases are also capable of oxidizing protein- and peptide-bound tyrosyl residues, resulting in the formation of inter- and intra-molecular crosslinks. Tyrosinases from apple (AT), potato (PT), the white rot fungus Pycnoporus sanguineus (PsT), the filamentous fungus Trichoderma reesei (TrT) and the edible mushroom Agaricus bisporus (AbT) were compared for their biochemical characteristics. The enzymes showed different features in terms of substrate specificity, stereo-specificity, inhibition, and ability to crosslink the model protein, α-casein. All enzymes were found to produce identical semiquinone radicals from the substrates as analyzed by electron spin resonance spectroscopy. The result suggests similar reaction mechanism between the tyrosinases. PsT enzyme had the highest monophenolase/diphenolase ratio for the oxidation of monophenolic l-tyrosine and diphenolic l-dopa, although the tyrosinases generally had noticeably lower activity on monophenols than on di- or triphenols. The activity of AT and PT on tyrosine was particularly low, which largely explains the poor crosslinking ability of the model protein α-casein by these enzymes. AbT oxidized peptide-bound tyrosine, but was not able to crosslink α-casein. Conversely, the activity of PsT on model peptides was relatively low, although the enzyme could crosslink α-casein. In the reaction conditions studied, TrT showed the best ability to crosslink α-casein. TrT also had the highest activity on most of the tested monophenols, and showed noticeable short lag periods prior to the oxidation.

Keywords
PT, tyrosinase from potato; AT, tyrosinase from apple; TrT, tyrosinase from Trichoderma reesei; PsT, tyrosinase from Pycnoporus sanguineus; AbT, tyrosinase from Agaricus bisporus; Y, tyrosine; G, glycineTyrosinase; Plant; Fungal; Specificity; Inhibition;
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 130, Issue 4, 15 July 2007, Pages 471–480
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