Biosynthesis and applications of alginates
Biosynthesis and applications of alginates
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DOI：
10.1016/s0141-3910(97)00179-1
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发表时间：
1998-01-01
影响因子：
5.9
通讯作者：
Valla, S
中科院分区：
文献类型：
--
作者：
Ertesvag, H;Valla, S
海藻酸盐是由甘露糖醛酸（M）和古洛糖醛酸（G）组成的线性多糖家族。该聚合物在广泛的工业应用中用作凝胶形成剂和增粘剂。它还用于封装细胞和酶。海藻酸盐的粘度主要取决于聚合物长度，而凝胶形成和水结合特性以及免疫原性程度则由G残基的分数和分布决定。目前，藻酸盐是通过收获褐藻来制造的，但实际上，这种聚合物也可以由属于固氮菌属和假单胞菌属的一些细菌产生。海藻酸盐的生物合成主要在铜绿假单胞菌中进行研究，其中许多涉及的蛋白质和基因也已被鉴定。在藻类和细菌中，聚合物首先以甘露糖醛酸的形式产生，然后通过甘露糖醛酸 C-5-差向异构酶进行差向异构化。已在铜绿假单胞菌和维氏固氮菌的藻酸盐基因簇中鉴定出编码周质差向异构酶的基因。 A. vinelandii 基因组还编码至少五种分泌型差向异构酶家族，每种差向异构酶在藻酸盐中引入不同的 G 分布。因此，这些酶可用于体外修饰藻酸盐以获得具有所需G含量和分布模式的多糖。此类藻酸盐可用于需要可重复和特定物理性质的应用。 (C) 1998 爱思唯尔科学有限公司。版权所有。
Alginate is a family of linear polysaccharides composed of mannuronic acid (M) and guluronic acid (G). The polymer is used as a gel-former and viscosifier in a wide range of industrial applications. It is also used for encapsulation of cells and enzymes. The viscosity of alginate is mainly dependent on the polymer length, while the gel-forming and water-binding properties and the degree of immunogenicity are determined by the fraction and distribution of G-residues. Alginates are currently manufactured by harvesting brown algae, but in nature the polymer is also produced by some bacteria belonging to the genera Azotobacter and Pseudomonas. The biosynthesis of alginate has been mostly studied in Pseudomonas aeruginosa, where many of the involved proteins and genes have also been identified. In both algae and bacteria the polymer is first produced as mannuronan, which is then epimerized by the enzyme mannuronan C-5-epimerase. A gene encoding a periplasmic epimerase has been identified in the alginate gene clusters of P. aeruginosa and Azotobacter vinelandii. The A. vinelandii genome also encodes a family of at least five secreted epimerases, each of which introduces different distributions of G in the alginate. These enzymes can therefore be used to modify alginates in vitro to obtain polysaccharides with the desired content and distribution pattern of G. Such alginates may become useful in applications where reproducible and specific physical properties are required. (C) 1998 Elsevier Science Limited. All rights reserved.