Sosnick T R, Benjamin D C, Novotny J, Seeger P A, Trewhella J
Life Sciences Division, Los Alamos National Laboratory, New Mexico 87545.
Biochemistry. 1992 Feb 18;31(6):1779-86. doi: 10.1021/bi00121a028.
For three different murine immunoglobulins (IgG subclasses 1, 2a, and 2b), the distances between their antigen-binding sites have been measured using neutron scattering from deuterated antigens complexed with proteated IgG. Neutron-scattering data were measured for each antibody-antigen complex in a 41% D2O solvent. Unlike the proteated antibody molecule, the deuterated antigens are strongly contrasted against the 41% D2O solvent and give rise to a scattering profile that contains an interference term related to the distance between the deuterated antigens. For all three subclasses, the damping of this interference term, which gives information on the relative flexibility of the antigen-binding sites, indicates that a single distance is inadequate to describe the observed scattering and a distribution of distances is needed. The scattering profile has been modeled for each subclass to give the mean distance between the antigens and the variance of this distance. For all three IgG subclasses, the mean distance is between 117 and 134 A, and the variance is large (approximately 40 A), indicating a high degree of flexibility of the Fab arms. Small-angle X-ray scattering measurements on the same samples are consistent with the neutron-scattering results.
对于三种不同的鼠免疫球蛋白（IgG亚类1、2a和2b），通过对与未氘代IgG复合的氘代抗原进行中子散射，测量了它们抗原结合位点之间的距离。在41%D2O溶剂中测量了每种抗体 - 抗原复合物的中子散射数据。与未氘代的抗体分子不同，氘代抗原与41%D2O溶剂形成强烈对比，并产生包含与氘代抗原之间距离相关的干涉项的散射图谱。对于所有三个亚类，该干涉项的阻尼给出了关于抗原结合位点相对灵活性的信息，表明单一距离不足以描述观察到的散射，需要距离分布。已对每个亚类的散射图谱进行建模，以给出抗原之间的平均距离和该距离的方差。对于所有三个IgG亚类，平均距离在117至134埃之间，方差很大（约40埃），表明Fab臂具有高度灵活性。对相同样品进行的小角X射线散射测量结果与中子散射结果一致。
