Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, R3T 2N2, Canada.
J Phys Chem B. 2011 Sep 29;115(38):11286-93. doi: 10.1021/jp206377b. Epub 2011 Sep 7.
Hydrodynamic studies of miniagrin indicate a molar mass that is 20% larger than the value calculated from the sequence of this genetically engineered protein. Consistent with this finding is the negative sign and also the magnitude of the second virial coefficient obtained from small-angle X-ray scattering measurements. The inference that miniagrin reversibly self-associates is confirmed by a sedimentation equilibrium study that yields an equilibrium constant of 0.24 L/g for a putative monomer-dimer interaction. Finally, Guinier analysis of the small-angle X-ray scattering (SAXS) results yields concentration-dependent values for the radius of gyration that may be described by the monomer-dimer model and respective R(g) values of 40 and 105 Å for the monomeric and dimeric miniagrin species. Although intermolecular protein interactions are endemic in the events leading to acetylcholine receptor aggregation by agrin, the matrix proteoglycan of which miniagrin is a miniaturized model, this investigation raises the possibility that agrin may itself self-associate.
水动力研究表明，miniagrin 的分子量比根据该基因工程蛋白序列计算出的值大 20%。与这一发现一致的是，从小角度 X 射线散射测量中获得的第二维里系数的符号和大小均为负。沉降平衡研究证实了 miniagrin 可可逆地自我缔合的推断，该研究得出了一个假定的单体-二聚体相互作用的平衡常数为 0.24 L/g。最后，对小角度 X 射线散射（SAXS）结果进行古尼埃分析，得到了旋转半径的浓度依赖性值，这些值可以用单体-二聚体模型来描述，单体和二聚体 miniagrin 物种的 R(g)值分别为 40 和 105 Å。虽然在神经递质乙酰胆碱受体聚集过程中，蛋白聚糖基质与 agrin 中的蛋白聚糖密切相关，但这种 miniagrin 是其微型模型，该研究提出了 agrin 本身可能自我缔合的可能性。
