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 β-1,4-linked glucosamine (deacetylated/D) and N-acetylglucosamine (acetylated/A) units. To address this hypothesis, we prepared partially-acetylated chitosan oligosaccharides from a chitosan polymer (DA=35%, DPw=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, but also observed apparent DA-dependent priming activity, with the ADDD+DADD fraction proving remarkably effective. 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 bona fide information-carrying molecules.

中文翻译：

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乙酰化模式定义了壳聚糖四聚体的引发活性

壳聚糖的生物活性取决于它们的聚合度 (DP) 和乙酰化度 (DA)。然而，信息也可以通过乙酰化 (PA) 模式携带：β-1,4-连接的氨基葡萄糖（脱乙酰/D）和 N-乙酰氨基葡萄糖（乙酰化/A）单元的序列。为了解决这一假设，我们使用具有不同底物和裂解特异性的重组壳聚糖水解酶从壳聚糖聚合物（DA=35%，DPw=905）制备部分乙酰化壳聚糖寡糖。将混合物分离成 DP4-DP12 级分，测试其在水稻细胞中的激发子和引发活性。我们证实这两种活性都受 DP 的影响，但也观察到明显的 DA 依赖性启动活性，其中 ADDD+DADD 部分证明非常有效。然后，我们比较了使用不同几丁质脱乙酰酶制备的所有四种单乙酰化四聚体，并观察到引发活性的显着差异。这首次证明 PA 影响壳聚糖的生物活性，壳聚糖现在可以被认为是真正的信息携带分子。