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Electronic Journal of Biotechnology

versão On-line ISSN 0717-3458

Resumo

FANCHINI TERRASAN, César Rafael; GUISAN, José Manuel  e  CANO CARMONA, Eleonora. Xylanase and β-xylosidase from Penicillium janczewskii: Purification, characterization and hydrolysis of substrates . Electron. J. Biotechnol. [online]. 2016, vol.19, n.5, pp.54-62. ISSN 0717-3458.  http://dx.doi.org/10.1016/j.ejbt.2016.08.001.

Background: Xylanases and β-D-xylosidases are the most important enzymes responsible for the degradation of xylan, the second main constituent of plant cell walls. Results: In this study, the main extracellular xylanase (XYL I) and p-xylosidase (BXYL I) from the fungus Penicillium janczewskii were purified, characterized and applied for the hydrolysis of different substrates. Their molecular weights under denaturing and non-denaturing conditions were, respectively, 30.4 and 23.6 kDa for XYL I, and 100 and 200 kDa for BXYL I, indicating that the latter is homodimeric. XYL I is highly glycosylated (78%) with optimal activity in pH 6.0 at 65°C, while BXYL I presented lower sugar content (10.5%) and optimal activity in pH 5.0 at 75°C. The half-lives of XYL I at 55, 60 and 65°C were 125,16 and 6 min, respectively. At 60°C, BXYL I retained almost 100% of the activity after 6 h. NH4+,Na+, DTT and β-mercaptoethanol stimulated XYL I, while activation of BXYL I was not observed. Interestingly, XYL I was only partially inhibited by Hg2+, while BXYL I was completely inhibited. Xylobiose, xylotriose and larger xylooligosaccharides were the main products from xylan hydrolysis by XYL I. BXYL I hydrolyzed xylobiose and larger xylooligosaccharides with no activity against xylans. Conclusion: The enzymes act synergistically in the degradation of xylans, and present industrial characteristics especially in relation to optimal activity at high temperatures, prolonged stability of BXYL I at 60°C, and stability of XYL I in wide pH range.

Palavras-chave : Xylanolytic enzymes; Enzyme characterization; Enzyme purification; Xylan hydrolysis; Xylooligosaccharides hydrolysis.

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