CONFORMATIONAL STUDIES OF ALPHA-GLUCANS
CONFORMATIONAL STUDIES OF ALPHA-GLUCANS
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DOI：
10.1002/bip.1972.360110707
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发表时间：
1972-01-01
期刊：
影响因子：
2.9
通讯作者：
RAO, VSR
中科院分区：
文献类型：
--
作者：
SATHYANARAYANA, BK;RAO, VSR
研究了连接对α-D-葡萄糖二糖和多糖可能构象以及可能的分子内氢键的影响。键性质的不同影响能量优先的构象；(1→2)键只导致右旋螺旋构象，(1→3)键导致延伸的以及左旋和右旋螺旋构象；(1→4)键导致右旋和左旋宽螺旋构象。相邻残基之间可能的氢键也取决于连接的性质。比较了α-D-葡聚糖和β-D-葡聚糖的构象数据，结果表明，三种类型的多糖中，链上相邻残基之间的有利构象和氢键都受到非均质碳原子构型的影响。根据能量计算，提出了结晶葡聚糖的可能构象(ϕM=−10°，ψM=−30°，ϕN=−23°，ψN=−19°)。这种构象包含两种类型的氢键，一种是(1→4)键上的0-2和0-3原子之间的氢键，另一种是链上(1−3)键上的0-2和0-4原子之间的氢键。结晶麦芽糖中可能存在麦芽糖单元(−10°，−30°)的构象与麦芽糖的最小能量构象相吻合。
A study of the effect of linkage on the possible conformations of di‐and polysaccharides of α‐D‐glucose and also the probable intramolecular hydrogen bonds has been made. The differences in the nature of linkage is shown to effect the energetically preferred conformations; (1 → 2) linkages lead only to righthanded helical conformations, (1 → 3) linkages lead to extended as well as both left and righthanded helical conformations; (1 → 4) linkages lead to both right‐and lefthanded wide helical conformations. The possible hydrogen bonds between adjacent residues are also dependent on the nature of the linkage. A comparison of the conformational data of α‐D‐glucans with those of β‐D‐glucans has indicated that the favored conformations and hydrogen bonds between contiguous residues in the chain are influenced by the configuration at the anomeric carbon atom in all the three types of polysaccharides. From the energy calculations a probable conformation (ϕM= −10°, ψM= −30°, ϕN= −23°, ψN= −19°) has also been proposed for crystalline mycodextran in conformity with x‐ray data. This conformation contains two types of hydrogen bonds between contiguous residues one between 0–2 and 0–3 atoms at (1 → 4) linkage and the other between 0−2 and 0–4 atoms at (1 → 3) linkage in the chain. The conformation of maltose unit (−10°,−30°) that is likely to occur in the crystalline mycodextran coincides with the minimum energy conformation of maltose.