The biological activity of chitosans depends on their
degree of polymerization (DP) and degree of acetylation (DA). However, information
could also be carried by the pattern of acetylation (PA): the sequence of <i>β</i>-1,4-linked glucosamine (deacetylated/D)
and <i>N</i>-acetylglucosamine (acetylated/A)
units. To address this hypothesis, we prepared partially-acetylated chitosan
oligosaccharides from a chitosan polymer (DA=35%, DP<sub>w</sub>=905) using recombinant
chitosan hydrolases with distinct substrate and cleavage specificities. The
mixtures were separated into fractions DP4–DP12, which were tested for elicitor
and priming activities in rice cells. We confirmed that both activities were
influenced by DP, <a>but also observed apparent DA-dependent
priming activity, with the ADDD+DADD fraction proving remarkably effective</a>.
We then compared all four mono-acetylated tetramers prepared using different
chitin deacetylases and observed significant differences in priming activity.
This demonstrates for the first time that PA influences the biological activity
of chitosans, which can now be recognized as <i>bona fide</i> information-carrying molecules
Possible involvement of proteolytic degradation of tyrosinase in the regulatory effect of fatty acids on melanogenesis
