The error-prone PCR technique has been widely used in order to
obtain thermostable enzymes more suitable for industrial conditions. The
Orpinomyces xynA mutant library allowed the selection of four thermostable
mutants (M1-M4). Molecular dynamics (MD) predicted an N-terminal tail as
being a destabilizing structural region and allowed further enhancing of the
mutant xylanases thermostability. Thus, removal of the 27 amino acid residues
enabled an increase in the enzyme half-life values (t1/2). However, besides the
improved thermostability, the large enzyme production and high catalytic
performance are also relevant for the biotechnological application of enzymes.
During the mutant enzymes production in E. coli, the IPTG induction protocol
allowed high expression levels of soluble and active xylanases. The mutant
xylanases without the 27 amino acid residues showed improved thermostability
and the shorter versions of M2 and M4 (named as SM2 and SM4) also presented a
good performance in more extreme pH conditions
