Soares Paulo A G, Queiroz Ismael N L, Santos Gustavo R C, Mourão Paulo A S, Pomin Vitor H
Instituto de Bioquímica Médica Leopoldo de Meis and Hospital Universitário Clementino Fraga Filho, Programa de Glicobiologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, 21941-913, Brazil.
Biopolymers. 2016 Nov;105(11):840-51. doi: 10.1002/bip.22922.
The sulfated fucan from the sea urchin Lytechinus variegatus is composed of the repetitive sequence [-3)-α-l-Fucp-4( OSO3-)-(1-3)-α-l-Fucp-2,4-di( OSO3-)-(1-3)-α-l-Fucp-2( OSO3-)-(1-3)-α-l-Fucp-2( OSO3-)-(1-]n . Conformation (of rings and chains) and dynamics of this tetrasaccharide-repeating sulfated fucan substituted by Na(+) , Ca(2+) , and Li(+) as counterions have been examined through experiments of liquid-state nuclear magnetic resonance spectroscopy. Scalar coupling and nuclear Overhauser effect (NOE)-based data have confirmed that all composing units occur as (1) C4 chair conformer regardless of the cation type, unit position within the repeating sequence, and sulfation type. Chain conformation determined by NOE signal pattern assisted by molecular modeling for a theoretical octasaccharide has shown a similar linear 3D structure for the three differently substituted forms. Data derived from spin-relaxation measurements have indicated a contribution of counterion type to dynamics. The calcium-based preparation has shown the highest mobility while the sodiated one showed the lowest mobility. The set of results from this work suggests that counterion type can affect the physicochemical properties of the structurally well-defined sulfated fucan. The counterion effect seems to impact more on the structural mobility than on average conformation of the studied sulfated glycan in solution.
来自多色刺海胆的硫酸化岩藻聚糖由重复序列[-3)-α-L-岩藻糖基-4(OSO₃⁻)-(1-3)-α-L-岩藻糖基-2,4-二(OSO₃⁻)-(1-3)-α-L-岩藻糖基-2(OSO₃⁻)-(1-3)-α-L-岩藻糖基-2(OSO₃⁻)-(1-]ₙ组成。通过液态核磁共振光谱实验，研究了以Na⁺、Ca²⁺和Li⁺作为抗衡离子的这种四糖重复硫酸化岩藻聚糖的（环和链的）构象及动力学。基于标量耦合和核Overhauser效应（NOE）的数据证实，无论阳离子类型、重复序列中的单元位置以及硫酸化类型如何，所有组成单元均以(1)C4椅式构象存在。通过分子模拟辅助的NOE信号模式确定的链构象表明，三种不同取代形式具有相似的线性三维结构。自旋弛豫测量得到的数据表明抗衡离子类型对动力学有影响。钙基制剂显示出最高的流动性，而钠基制剂显示出最低的流动性。这项工作的一系列结果表明，抗衡离子类型可以影响结构明确的硫酸化岩藻聚糖的物理化学性质。抗衡离子效应似乎对结构流动性的影响比对溶液中所研究的硫酸化聚糖的平均构象的影响更大。
