The Conformational Energy of Maltose and Amylose
The Conformational Energy of Maltose and Amylose
复制标题
麦芽糖和直链淀粉的构象能
DOI：
10.1021/ma60017a605
复制
发表时间：
1970
期刊：
影响因子：
5.5
通讯作者：
W. Dimpfl
中科院分区：
文献类型：
--
作者：
K. D. Goebel;D. Brant;W. Dimpfl
摘要;本文根据环己直链淀粉和甲基麦芽糖苷的晶体结构，用结构模型计算了螺旋直链淀粉及其二聚体麦芽糖的构象能。已经采用了考虑分子内货车德瓦耳斯、库仑和氢键相互作用的势函数。分子内氢键被发现大大提高了某些螺旋构象的稳定性，也有利于货车德瓦尔斯相互作用的基础上。库仑相互作用似乎使空间允许的构象内的域的构象能可以忽略不计的贡献。对应于结晶直链淀粉V的构象发生在最低能量的右手和左手螺旋的直接域中。对应于天然直链淀粉B的构象在稍高的能量下发生，推测是由于忽略了分子间的相互作用。左手V直链淀粉被发现是能量低于其右手对应的2.6千卡mol-1，在本螺旋能量计算的不确定性的可能极限附近的差异。描述了直链淀粉V到具有相同手性的直链淀粉B的容易转化，并且根据所获得的结果，认为V到B转变中的手性逆转是不可能的。
ABSTRACT; The conformational energies of helical amylose and its dimeric skeletal unit maltose havebeen calculated using structural models based upon thecrystal structures of cyclohexaamylose and methyl ß-maltoside. Potential functions which account for intramolecular van der Waals, coulombic, and hydrogen-bonded interactions have been employed. Intramolecular hydrogen bonding is found greatly to enhance the stability of certain helical conformations favored also on the basis of van der Waals interactions. Coulombic interactions appear to make negligible contributions to the conformational energy within the domain of sterically allowed conformations. Conformations corresponding to crystalline amylose V occur in the immediate domains of the least energetic right-and left-handed helices. Conformations corresponding to native amylose B occur at somewhat higher energies, presumablyowing to neglect of intermolecular interactions. Left-handed V amylose is found to be less energetic than its right-handed counterpart by 2.6 kcal mol-1, a difference near the probable limits of uncertainty in the present calculations of helix energy. Facile conversions of amylose V to amylose B possessing the same chirality are described, and it is argued on the basis of results obtained that reversal of chirality in V to B transitions is improbable.