Partial purification and characterisation of two actinomycete tyrosinases and their application in cross-linking reactions

• Published in: Journal of molecular catalysis. B, Enzymatic Vol. 122; pp. 353 - 364
• Main Authors: Le Roes-Hill, Marilize, Palmer, Zaida, Rohland, Jeffrey, Kirby, Bronwyn Michelle, Burton, Stephanie Gail
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.12.2015
• Subjects: Biochemical characterisation; Cross-linking; Industrial application; Streptomyces; Tyrosinase; Streptomyces; Cross-linking; Biochemical characterisation; Industrial application; Tyrosinase
• ISSN: 1381-1177; 1873-3158
• DOI: 10.1016/j.molcatb.2015.10.012

[Display omitted] ⿢Partial purification of two extracellular tyrosinases from Streptomyces spp.⿢Organic solvent resistance exhibited by tyrosinases.⿢Atypical characteristics, e.g., resistance to arbutin and SDS.⿢Catalysed cross-linking reactions of proteins, e.g., gelatine and casein. Actinomycetes are a ubiquitous group of bacteria, and are hypothesised to produce tyrosinases for protection against the potential toxic effect of phenolic compounds and for the production of melanin. In this study, tyrosinase production by Streptomyces pharetrae CZA14T (CZA14Tyr) and Streptomyces polyantibioticus SPRT (SPRTyr) was optimised. The enzymes were partially purified and biochemically characterised to determine their suitability for industrial applications. SPRTyr was stable up to 40°C and at pH 4.5⿿10.0, while CZA14Tyr was stable up to 40°C and at pH 6.5⿿10.0. The enzymes showed variable stability in the presence of water-miscible organic solvents and were able to oxidize l-DOPA in the presence of these solvents. A limited inhibitory effect was observed with arbutin, EDTA, sodium chloride and sodium dodecyl sulphate, while both enzymes were strongly inhibited by the reducing agents used in this study. Inhibition of enzyme activity was observed in the presence of 1mM Cu2+ and 5mM Co2+ for SPRTyr, and 5mM Fe2+ and 5mM Zn2+ for CZA14Tyr. When applied in various cross-linking reactions both tyrosinases were able to cross-link casein and gelatine in the absence of a phenolic compound, showing potential for application in the food industry and for the production of biomaterials.