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Macromolecular replication during lignin biosynthesis

策马入林添加于 2013-4-15 23:08 | 1554 次阅读 | 0 个评论

作者
Chen Y-R, Sarkanen S
摘要
Lignins play a crucial role in the cell-wall architecture of all vascular plants. They are composed of p-hydroxyphenylpropanoid units interconnected through covalent bonds formed during lignol radical coupling between six different pairs of atomic centers. For 50years, the primary structures of lignins have been thought to be random, but for a number of reasons such an assumption is not tenable. For example, it has been reported that, by simple physicochemical means, the rather recalcitrant lignins in spruce wood can be decisively separated into two fractions containing quite dissimilar biopolymer chains. Thus, a paradigm shift should be imminent, and a detailed working hypothesis for the mechanism of lignin biosynthesis would be invaluable in delineating how the process of macromolecular lignin assembly can be properly investigated. In conjunction with an earlier experimental result, an explicit model for a template dehydropolymerization process has been developed that describes how lignin primary structure is replicated. The strengths of the powerful noncovalent interactions have been calculated that control the transient placement of lignol radicals about to undergo coupling on a double-stranded lignin template. These elementary steps engender, in the growing daughter chain, a primary structure identical to that of the distal template strand. The interactions are governed by dynamical electron correlation in the pi-orbitals of each immobilized lignol radical and the complementary aromatic ring in the antiparallel proximal strand. The resulting noncovalent forces are computed to be stronger than those stabilizing GC/CG base pairs in DNA double-helices, but the mechanism of replication is fundamentally different from that of any other biopolymer.
详细资料
- 关键词: Cell Wall/chemistry/metabolism; Lignin/*biosynthesis/*chemistry/metabolism; *Models, Chemical; Models, Molecular; Molecular Conformation; Plant Cells
- 文献种类: Journal Article
- 期刊名称: Phytochemistry
- 期刊缩写: Phytochemistry
- 期卷页: 2010年第71卷第4期 453-462页
- 地址: Department of Bioproducts and Biosystems Engineering, University of Minnesota, St. Paul, MN 55108, USA
- ISBN: 0031-9422
学科领域生物医药 » 生物学
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