Kolattukudy P E
Ohio State University, 206 Rightmire Hall, 1060 Carmack Rd, Columbus, OH 43210, USA.
Adv Biochem Eng Biotechnol. 2001;71:1-49. doi: 10.1007/3-540-40021-4_1.
Polyesters occur in higher plants as the structural component of the cuticle that covers the aerial parts of plants. This insoluble polymer, called cutin, attached to the epidermal cell walls is composed of interesterified hydroxy and hydroxy epoxy fatty acids. The most common chief monomers are 10,16-dihydroxy C16 acid, 18-hydroxy-9,10 epoxy C18 acid, and 9,10,18-trihydroxy C18 acid. These monomers are produced in the epidermal cells by omega hydroxylation, in-chain hydroxylation, epoxidation catalyzed by P450-type mixed function oxidase, and epoxide hydration. The monomer acyl groups are transferred to hydroxyl groups in the growing polymer at the extracellular location. The other type of polyester found in the plants is suberin, a polymeric material deposited in the cell walls of a layer or two of cells when a plant needs to erect a barrier as a result of physical or biological stress from the environment, or during development. Suberin is composed of aromatic domains derived from cinnamic acid, and aliphatic polyester domains derived from C16 and C18 cellular fatty acids and their elongation products. The polyesters can be hydrolyzed by pancreatic lipase and cutinase, a polyesterase produced by bacteria and fungi. Catalysis by cutinase involves the active serine catalytic triad. The major function of the polyester in plants is as a protective barrier against physical, chemical, and biological factors in the environment, including pathogens. Transcriptional regulation of cutinase gene in fungal pathogens is being elucidated at a molecular level. The polyesters present in agricultural waste may be used to produce high value polymers, and genetic engineering might be used to produce large quantities of such polymers in plants.
聚酯作为覆盖植物地上部分的角质层的结构成分存在于高等植物中。这种不溶性聚合物称为角质，附着在表皮细胞壁上，由酯交换的羟基和羟基环氧脂肪酸组成。最常见的主要单体是10,16 - 二羟基C16酸、18 - 羟基 - 9,10环氧C18酸和9,10,18 - 三羟基C18酸。这些单体在表皮细胞中通过ω-羟基化、链内羟基化、由P450型混合功能氧化酶催化的环氧化以及环氧化物水合作用产生。单体酰基在细胞外位置转移到正在生长的聚合物中的羟基上。植物中发现的另一种聚酯是木栓质，当植物由于来自环境的物理或生物胁迫，或在发育过程中需要建立屏障时，它是一种沉积在一两层细胞细胞壁中的聚合材料。木栓质由源自肉桂酸的芳香域和源自C16和C18细胞脂肪酸及其延伸产物的脂肪族聚酯域组成。聚酯可以被胰脂肪酶和角质酶水解，角质酶是一种由细菌和真菌产生的聚酯酶。角质酶的催化作用涉及活性丝氨酸催化三联体。植物中聚酯的主要功能是作为抵御环境中的物理、化学和生物因素（包括病原体）的保护屏障。真菌病原体中角质酶基因的转录调控正在分子水平上得到阐明。农业废弃物中存在的聚酯可用于生产高价值聚合物，基因工程可能用于在植物中大量生产此类聚合物。
