by suspension in 90% sorbitol. Under these conditions, the half life
of the enzyme was 60 min at 130 °C (Simpson et al. 1991). Analysis of the
molecular basis for thermostable xylanases began with in vitro mutagenesis of
the xylanase from Caldocellum saccharolyticum (Luthi et al. 1992). The
enzyme shows strong sequence homology with other mesophilic xylanases, but
the presence of several charged amino acids that could form salt bridges could
account for thermostability.