New developments of polysaccharide synthesis via enzymatic polymerization.
New developments of polysaccharide synthesis via enzymatic polymerization.
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DOI：
10.2183/pjab/83.215
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发表时间：
2007-12
期刊：
影响因子：
--
通讯作者：
Kobayashi S
中科院分区：
文献类型：
--
作者：
Kobayashi S
本文综述了本课题组主要研究的多糖体外合成方法--酶促聚合法。多糖通过糖基供体和糖基受体之间的重复糖基化反应形成。发现水解酶作为催化剂非常有效，其中单体是基于“过渡态类似物底物”（TSAS）的新概念设计的;用于缩聚的氟化糖单体和用于开环加聚的糖恶唑啉单体。酶促聚合使天然多糖如纤维素、木聚糖、几丁质、透明质酸和软骨素以及非天然多糖如纤维素-几丁质杂合物、透明质酸-软骨素杂合物等的首次体外合成成为可能。透明质酸酶的超催化作用被公开为不寻常的酶多催化剂功能。突变酶在合成和机理研究中非常有用。通过SEM、TEM和组合SAS方法对酶促聚合的原位观察揭示了聚合和通过延长多糖分子形成的高阶分子结构的自组装的机制。
This review focuses on the in vitro synthesis of polysaccharides, the method of which is “enzymatic polymerization” mainly developed by our group. Polysaccharides are formed by repeated glycosylation reactions between a glycosyl donor and a glycosyl acceptor. A hydrolysis enzyme was found very efficient as catalyst, where the monomer is designed based on the new concept of a “transition-state analogue substrate” (TSAS); sugar fluoride monomers for polycondensation and sugar oxazoline monomers for ring-opening polyaddition. Enzymatic polymerization enabled the first in vitro synthesis of natural polysaccharides such as cellulose, xylan, chitin, hyaluronan and chondroitin, and also of unnatural polysaccharides such as a cellulose–chitin hybrid, a hyaluronan–chondroitin hybrid, and others. Supercatalysis of hyaluronidase was disclosed as unusual enzymatic multi-catalyst functions. Mutant enzymes were very useful for synthetic and mechanistic studies. In situ observations of enzymatic polymerization by SEM, TEM, and combined SAS methods revealed mechanisms of the polymerization and of the self-assembling of high-order molecular structure formed by elongating polysaccharide molecules.