Alba K, Bingham R J, Kontogiorgos V
Department of Biological Sciences, University of Huddersfield, HD1 3DH, United Kingdom.
Biopolymers. 2017 Jun;107(6). doi: 10.1002/bip.23016.
Mesoscopic structure of pectin with different molecular characteristics was investigated by means of small angle X-ray scattering (SAXS), electrokinetic measurements and data modelling. The influence of a broad range of pH (2-7) on chain conformation in the dilute and semi-diluted regime was investigated. Scattering data and concomitant analysis revealed two length scales at all environmental conditions studied. pH showed greater influence at acidic values (pH 2.0) enhancing the globular component of the structure due to association of galacturonic acid residues. Double logarithmic scattering intensity plots revealed fractal dimensions of 1.9 ± 0.2 in the low-q regime and 1.5 ± 0.2 in the high q-region, irrespectively of the specific environment. Increase in branching of RG-I regions of the polysaccharide chains enhanced the compact conformation irrespectively of the pH or concentration. The present work shows that radical changes in pectin conformation can be induced only under strongly acidic conditions a finding that has important consequences in tailoring the technological performance of these biopolymers.
通过小角X射线散射（SAXS）、电动测量和数据建模研究了具有不同分子特征的果胶的介观结构。研究了广泛pH范围（2-7）对稀溶液和半稀溶液体系中链构象的影响。散射数据及相关分析表明，在所研究的所有环境条件下都存在两个长度尺度。在酸性值（pH 2.0）时，pH的影响更大，由于半乳糖醛酸残基的缔合，增强了结构的球状成分。双对数散射强度图显示，在低q区域分形维数为1.9±0.2，在高q区域为1.5±0.2，与特定环境无关。多糖链RG-I区域分支的增加增强了紧密构象，与pH或浓度无关。目前的研究表明，只有在强酸性条件下才能诱导果胶构象发生根本性变化，这一发现对调整这些生物聚合物的技术性能具有重要意义。
