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Title: Secretory expression of recombinant small laccase from Streptomyces coelicolor A3(2) in Pichia pastoris
Authors: Yadava, Deepti 
Ranjana, Bibhuti 
Mchunu, Nokuthula 
Le Roes-Hill, Marilize 
Kudanga, Tukayi 
Keywords: Dye decolourization;Pichia secretory expression;Small laccase
Issue Date: 2017
Publisher: Elsevier
Journal: International Journal of Biological Macromolecules 
Abstract: This work reports for the first time the secretory expression of the small laccase (SLAC) from Streptomyces coelicolor A3(2) in Pichia pastoris. Using an AOX1 promoter and factor as a secretion signal, the recombinant P. pastoris harbouring the laccase gene (rSLAC) produced high titres of extracellular laccase (500 ± 10 U/l), which were further increased seven fold by pre-incubation at 80 ◦C for 30 min. The enzyme (∼38 kDa) had an optimum activity at 80 ◦C, but optimum pH varied with substrate used. Km values for ABTS, SGZ and 2,6-DMP were 142.85 M, 10 M and 54.55 M and the corresponding kcat values were 60.6 s−1, 25.36 s−1 and 27.84 s−1, respectively. The t1/2 values of the rSLAC at 60 ◦C, 70 ◦C, 80 ◦C were 60 h, 32 h and 10 h, respectively. The enzyme deactivation energy (Ed) was 117.275 kJ/mol while G, H and S for thermal inactivation of the rSLAC were all positive. The rSLAC decolourised more than 90% of Brilliant Blue G and Trypan Blue dye in 6 h without the addition of a mediator. High titres of SLAC expressed in P. pastoris enhance its potential for various industrial applications.
ISSN: 1879-0003
Appears in Collections:Appsc - Journal Articles (DHET subsidised)

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