Chitosan (KitoNor; fraction of acetylation (FA) 0.15;
viscosity average molecular weight (MWv) 33.4 kDa and DPn 206, was obtained from Norwegian Chitosan (Gardermoen, Norway). CHOS with varying level of
polymerization were produced from chitosan (DPn 206)
by enzymatic hydrolysis for different lengths of time,
using chitosanase ScCsn46A as described by Heggset
and coworkers (Heggset et al. 2010). Briefly,
chitosanase ScCsn46A, originally from Streptomyces
coelicolor q9rj88, was purified from the culture supernatant
of a recombinant Escherichia coli BL21Star
(DE3) strain, following the published protocol, without
removal of the (His)6-tag after purification. The enzyme
was dialyzed against Tris–HCl (20 mM) at pH 8 and
stored at 4 °C.