Molecular Aspects of B-Glucan Biosynthesis in Higher Plants

在高等植物中，β -(1,3)连接的葡聚糖和可能的纤维素的生物合成是由质膜酶葡聚糖合成酶（udp -葡萄糖：(1,3)- β -葡聚糖合成酶）催化的。为了了解细胞壁多糖生物生成和创面愈合调控的生化基础，有必要对多糖合酶进行鉴定和表征。葡聚糖合成酶在植物组织中普遍存在，但已被证明是一种难以通过标准蛋白质分离技术纯化到均匀性的酶。现在，使用CHAPS洗涤剂的差异增溶、凝胶过滤层析和产品包埋，可以从一系列植物来源获得稳定和高度富集的酶制剂。这项研究将解决长期存在的问题，即β -(1,3)和β -(1,4)连接的葡聚糖是由一种酶合成的，还是由几种酶合成的，其中每种酶都是不同的，形成一种连接类型。此外，明确鉴定构成葡聚糖合酶复合物的多肽将有助于鉴定和克隆植物细胞壁生物发生中重要酶的基因或基因。纤维素是一种非常丰富的生物聚合物，在植物细胞中起着结构作用。由于很难从细胞壁中分离出所涉及的酶，人们对其生物合成还不完全了解。这个项目的重点是主要的调控酶，并将提供细胞壁是如何形成和保持完整的重要信息。

The biosynthesis of beta-(1,3) linked glucans and possibly cellulose in higher plants is catalyzed by the plasma membrane enzyme glucan synthase (UDP-glucose:(1,3)-beta-glucan synthase). To understand the biochemical basis for the regulation of cell wall polysaccharide biogenesis and wound healing, it is necessary to identify and characterize the polysaccharide synthases. Glucan synthase is ubiquitous in plant tissue but has proven to be a stubborn enzyme to purify to homogeneity by standard protein fractionation techniques. It is now possible to obtain stabilized and highly-enriched enzyme preparations from a range of plant sources using differential solubilization with the detergent CHAPS, gel filtration chromatography and product entrapment. This research will resolve the longstanding question of whether beta-(1,3) and beta-(1,4) linked glucans are biosynthesized by one enzyme or by several where each is distinct for the formation of one linkage type. Furthermore, unambiguous identification of the polypeptides which comprise the glucan synthase complex will facilitate identification and cloning of the gene or genes which code for important enzymes in plant cell wall biogenesis. Cellulose, an immensely abundant biopolymer, serves a structural role in plant cells. Its biosynthesis is only incompletely understood because of the difficulties in isolating the enzymes involved from cell walls. This project focuses on the major regulated enzyme and will provide important information on how cell walls are made and kept intact.