【作者】 孙玉敬；

【导师】 庞杰；

【作者基本信息】 福建农林大学 ， 食品科学， 2006， 硕士

【摘要】 本文以葡甘聚糖为试材，运用分子模拟同仪器分析相结合的手段，预测了葡甘聚糖分子链的高级结构，分析了无机分子对其结构、性能的影响，探讨了葡甘聚糖与卡拉胶微观作用机理。主要研究内容与结果如下： 1．葡甘聚糖单链高级结构的预测 利用Hyperchem7.0、VM2.0分子结构计算软件采用分子动力学和分子力学的方法，以真空中葡甘聚糖单链为研究模型，研究了聚合度、取代基对动态构象的影响及影响链构象的作用力。首次提出了KGM链的动态模型，得到了以下结果：聚合度影响其链形态和稳定性，对于高聚合度的魔芋葡甘聚糖来说，其链呈现无规卷曲状态且稳定性下降，在整个动态运动过程中KGM链脱乙酰基前后都呈现无规卷曲状态，而且其伸展和卷曲的变化是周期性的，表现出了很好的柔性，说明乙酰基不是影响其链形态的主要因素，二面角能和静电作用是真空中影响单链构象的主要的键合作用力和非键合作用力，但是乙酰基对氢键作用的影响较大。 2．无机分子对葡甘聚糖溶液体系结构性能影响的研究 利用Hyperchem7.0分子结构计算软件，采用分子动力学及红外光谱、核磁共振等技术，对无机分子对葡甘聚糖体系的影响进行分析，很好的解释了性能变化的结构原因，结合以往的研究及参考文献得出以下结论：KGM在碱性条件下由于化学作用乙酰基的脱除分子间氢键作用的加强提高了凝胶强度，分子间氢键的主要作用位点是葡萄糖的0(6)与甘露糖的0(2)之间；硼与KGM形成的分子内和分子间配合作用及分子间作用力氢键的增强是KGM特性粘度和致密性提高的主要原因，分子间型配位反应发生在葡萄糖和甘露糖两个糖环之间的几率最大；加入尿素后，表现为宏观性能的下降，葡甘聚糖氢键网络被破坏，氢键的作用位点由甘露糖的0(2)、0(3)变为0(4)，葡萄糖的0(3)、0(6)变为0(1)、0(2)。 3．葡甘聚糖与卡拉胶共混作用的研究 利用Hyperchem7.0分子结构计算软件运用分子动力学方法、DSC、红外光谱技术，研究了葡甘聚糖与卡拉胶的微观结构及作用过程，揭示了性能变化的结构原因和分子之间的作用位点。得出了以下结论：葡甘聚糖同卡拉胶共混后通过分子间氢键作用形成了强度高、弹性好的热可逆凝胶。其凝胶强度与单一胶相比较，凝胶特性得到了很大的改善。通过红外光谱可以发现形成复合溶胶后化学基团没有发生本质上的改变，但是氢键缔合作用增强；通过DSC分析可以发现仅出现1个吸热峰，两种生物大分子达到了相容的结果，经过分子动力学模拟表明，与单一体系比较，葡甘聚糖与卡拉胶共混时稳定性提高，分子间氢键作用力明显增强，主要的作用位点是葡甘聚糖的上甘露糖的0(2)、0(4)、0(6)、乙酰基位置及卡拉胶上糖环上的0(6)、硫酸基。更多还原

【Abstract】 Using molecular simulation and modern instruments analysis, the chain three-dimensional structure was predicted, The influence of inorganic compound on its structure and property in solution system as well as microcosmic interaction process between KGM and carrageen were researched. The details are specified as follows:1 Prediction of KGM chain structureUsing computing molecular structure software: Hyperchem7.0 VM2.0, methods of molecular dynamics and molecular mechanics and the model of single KGM chain , polymerization degree as well as the influence of substitution group on dynamics conformation and the interaction affecting chain conformation were researched. For the first time, the dynamics changing process of KGM chain in vacuum is proposed, We obtained the following results: polymerization degree influences the stability and shapes of the chain, the chain stability drops with the increasing of polymerization degree, for the high polymerization degree KGM, KGM chain takes on irregular curl state; acetyl group is not the main factor influencing chain conformation , during the course of dynamics movement KGM chain takes on irregular curl state before and after acetyl group was doffed, Extending and curling states change periodicity and has good flexibility. The electrostatic energy is the main non-bonded function, Dihedral energy is the main bonded function, but acetyl group is the main factor influencing H-Bonds.2 Research of inorganic compound’s influence on structure and property of KGM solution systemUsing computing molecular structure software: Hyperchem7.0, methods of molecular dynamics and technology of IR and NMR, SAR (Structure -activity relationships) of KGM was analyzed , the structure reason of property change was well explained. We obtained the following results combining past research and references: Under alkaline conditions the increase of intra-molecular hydrogen bond interaction improves gel strength because of chemistry function in which acetyl group was taken out, and the main intra-molecular hydrogen bond function point is between 0(6) of glucose and 0(2) of mannose; After borax and KGM functioned ,the intrinsic viscosities increases and the KGM film is more compact and uniform, the reason is that the coordination function of inter-molecules and intra-molecules and the increase of intra-molecular hydrogen bond, the coordination reaction of intra-molecules most takes place the position between glucose and mannose; when urea is added the solution system , KGM hydrogen bond network is destroyed , viscosity is dropped, the hydrogen bond numbers reduces, the main hydrogen bond function points changes O(2) . O(3)of mannose and O(3) O(6) of glucose into O(4 )of mannose and O (1)> O (2) of glucose.3 Research of KGM and carrageen mixing functionUsing computing molecular structure software: Hyperchem7.0, methods of molecular dynamics and technology of IR and DSC, the microcosmic structure of KGM and carrageen compound and interaction process was researched, the structure reason why property changes and interaction position among intra -molecules were found. We obtained the following results: The heat reversible gel which has high strength good elasticity is formed by intermolecular hydrogen bond function after KGM mixed with carrageen, comparing with single gel, mixing gel improves gel property obviously. By IR we found that chemical group does not change in essence but hydrogen-bonded function increases; By DSC analysis only one peak occurs ,two kinds polymers更多还原