McCullagh C M, Gupta R, Jamieson A M, Blackwell J
Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106-7202, USA.
Int J Biol Macromol. 1996 Jun;18(4):247-53. doi: 10.1016/0141-8130(95)01086-6.
Rheological measurements have been performed on three molecular weight fractions of purified canine submaxillary mucin (CSM) dissolved in the chaotropic solvent 6 M guanidine hydrochloride (GdnHCI). Solutions of the lower molecular weight fractions are viscoelastic sols, and their dynamic moduli can be scaled with respect to molecular weight and concentration according to linear viscoelasticity theory. In contrast, preparations of the highest molecular weight fraction form viscoelastic gels that exhibit an equilibrium shear modulus, Ge', which scales with mucin concentration as Ge' approximately c3. Amino acid and carbohydrate analyses of all three fractions are similar; thus, the differences in rheological behavior are attributed to molecular weight differences, which affect the degree of coil overlap in solutions of a given concentration. These observations demonstrate conclusively that mucin glycoproteins of high molecular weight form gels under conditions in which the mucin chains physically interpenetrate, even when non-covalent intermolecular interactions are extensively disrupted. A comparison of these results with previous studies of purified submaxillary and tracheobronchial mucins indicates that the carbohydrate side-chain length, in addition to molecular weight, is an important determinant of the observed elastic response and the ability to form physical gels.
已对溶解在离液溶剂6M盐酸胍（GdnHCI）中的纯化犬下颌粘蛋白（CSM）的三个分子量级分进行了流变学测量。较低分子量级分的溶液是粘弹性溶胶，根据线性粘弹性理论，其动态模量可相对于分子量和浓度进行标度。相比之下，最高分子量级分的制剂形成粘弹性凝胶，表现出平衡剪切模量Ge'，其随粘蛋白浓度按Ge'≈c3标度。所有三个级分的氨基酸和碳水化合物分析相似；因此，流变行为的差异归因于分子量差异，分子量差异影响给定浓度溶液中卷曲重叠的程度。这些观察结果确凿地表明，即使非共价分子间相互作用被广泛破坏，高分子量的粘蛋白糖蛋白在粘蛋白链物理相互渗透的条件下仍会形成凝胶。将这些结果与先前对纯化的下颌和气管支气管粘蛋白的研究进行比较表明，除分子量外，碳水化合物侧链长度是观察到的弹性响应和形成物理凝胶能力的重要决定因素。
