BIOSYNTHESIS OF PLANTEOSE IN SESAMUM-INDICUM
BIOSYNTHESIS OF PLANTEOSE IN SESAMUM-INDICUM
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DOI：
10.1016/0014-5793(80)80882-9
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发表时间：
1980-01-01
期刊：
影响因子：
3.5
通讯作者：
DEY, PM
中科院分区：
文献类型：
--
作者：
DEY, PM
根据D-半乳糖基与蔗糖分子的连接方式，三糖-单-Y-D-半乳糖基蔗糖可能有八种异构体[11.其中六种已从不同的植物来源分离和表征[11.三种异构体(未命名成员)被怀疑是结构相关的高级寡糖部分降解的产物[L-5]。另外三种异构体，植物糖、棉子糖和伞形糖是许多植物种子的主要储备低聚糖[11.已证明后两个成员的生物合成是通过以UDP-半乳糖为半乳糖供体的途径进行的[6-131.然而，在棉子糖的合成中，半乳糖醇[O+D-半乳糖基-(1-+L)-肌醇]也可以作为半乳糖的重要供体[14,151]。关于植物糖[&Y-D-半乳糖基-(1+6)-/3-D-呋喃果糖-(1+6)-/3-D-呋喃果糖基-吡喃葡萄糖苷]的生物合成，文献报道有限；有人认为这种低聚糖可能是在α-半乳糖苷酶的催化下通过Ar-D-半乳糖基转移到蔗糖来合成的。涉及低能半乳糖供体的类似的酶半乳糖化早已被证明[17-201。然而，这些反应需要高度集中的供体和受体。本通讯描述了芝麻低聚糖植物糖家族的鉴定及其通过UDP-半乳糖介导的途径在芝麻种子中的合成。缩写：PL，植物糖；PL，(芝麻糖)和PI，分别是植物糖、四糖和五糖的较高同系物，包含附加在分子中现有半乳糖基团的CD上的铜半乳糖部分
Eight isomers of the trisaccharide, mono-&y-D-galactosyl sucrose are possible according to the way in which the D-galactosyl group is linked to the sucrose molecule [11. Six of these have been isolated and characterised from various plant sources [11. Three of the isomers (unnamed members) are suspected to be formed as products of partial degradation of structurally related higher oligosaccharides [l-5]. The other three isomers, planteose, raffinose and umbelliferose are major reserve oligosaccharides of the seeds of a number of plant species [11. The biosynthesis of the latter two members have been shown to proceed through a pathway involving UDP-galactose as the galactosyl donor [6-131. However, in the synthesis of raffinose, galactinol [O+ D-galactopyranosyl-(1-+ l)-myo-inositol] can also act as an important galactosyl donor [14,151. As regards the biosynthesis of planteose [&y-D-galactopyranosyl-( 1+ 6)-/3-D-fructofuranosyl aD-glucopyranoside], only limited work has been reported in the literature; it was suggested that this oligosaccharide might be synthesised through ar-D-galactosyl transfer to sucrose, catalysed by a-galactosidase [161. Similar enzymic galactosylation involving low-energy galactosyl donors have long been demonstrated[17-201. These reactions, however, require high concentrations of donors and acceptors. This communication describes identification of the planteose family of oligosaccharides and their synthesis through UDP-galactose mediated pathway in the seeds of Sesamum indicum(sesame).Abbreviations: Pl, planteose; Pl,(sesamose) and PI,, the higher homologs of planteose, tetra-and pentasaccharides, respectively, containing additional cu-Dgalactose moiety attached to Cd of the existing Dgalactosyl group of the molecule