Chitosans are linear, binary co-polymers of glucosamine and N-acetylglucosamine residues with interesting material properties and promising biological activities. Many of the biological activities of chitosan polymers are thought to be conveyed by their oligomeric breakdown products generated in situ by the action of sequence-specific chitosan hydrolases yielding partially acetylated chitosan oligosaccharides (paCOS) with partially or fully defined degrees of polymerisation (DP), fractions of acetylation (F_A), and patterns of acetylation (PA). In this review, we summarize the state of the art concerning the production and analysis of defined chitosan oligomers as well as our current knowledge on the structure-function relationships of their bioactivities. Recent progress in this field was initially driven by the availability of increasing numbers of recombinant chitosan hydrolases with known and defined subsite specificities combined with improved chromatographic separation techniques for their products. This allowed insights into the roles of DP and F_A in defining the biological activities of paCOS. More recently, the development is fuelled by the availability of equally well-defined recombinant chitin deacetylases in conjunction with improved mass spectrometric analysis tools for the structural characterisation of their products. This is currently enabling us to begin investigating the role of PA in defining biological activities.

壳聚糖是葡糖胺和N-乙酰葡糖胺残基的线性二元共聚物，具有令人感兴趣的材料特性和有前途的生物活性。壳聚糖聚合物的许多生物学活性被认为是通过序列特异性壳聚糖水解酶的作用原位产生的寡聚分解产物来传达的，这些产物产生部分乙酰化的壳聚糖寡糖（paCOS），具有部分或完全限定的聚合度（DP），乙酰化的级分（˚F_甲）和乙酰化模式（PA）。在这篇综述中，我们总结了有关确定的壳聚糖低聚物的生产和分析的最新技术，以及我们目前对其生物活性的结构-功能关系的了解。该领域的最新进展最初是由越来越多的具有已知和确定的亚位点特异性的重组壳聚糖水解酶的可得性以及改进其产品的色谱分离技术共同驱动的。这可以深入了解DP和F _A的作用在定义paCOS的生物学活性方面。最近，可得的定义相同的重组几丁质脱乙酰基酶与改进的质谱分析工具一起用于其产品的结构表征，推动了这一发展。当前，这使我们能够开始研究PA在定义生物活动中的作用。