He X M, Rüker F, Casale E, Carter D C
Space Science Laboratory, Marshall Space Flight Center, Huntsville, AL 35812.
Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):7154-8. doi: 10.1073/pnas.89.15.7154.
The three-dimensional structure of a human monoclonal antibody (Fab), which binds specifically to a major epitope of the transmembrane protein gp41 of the human immunodeficiency virus type 1, has been determined by crystallographic methods to a resolution of 2.7 A. It has been previously determined that this antibody recognizes the epitope SGKLICTTAVPWNAS, belongs to the subclass IgG1 (kappa), and exhibits antibody-dependent cellular cytotoxicity. The quaternary structure of the Fab is in an extended conformation with an elbow bend angle between the constant and variable domains of 175 degrees. Structurally, four of the hypervariable loops can be classified according to previously recognized canonical structures. The third hypervariable loops of the heavy (H3) and light chain (L3) are structurally distinct. Hypervariable loop H3, residues 102H-109H, is unusually extended from the surface. The complementarity-determining region forms a hydrophobic binding pocket that is created primarily from hypervariable loops L3, H3, and H2.
一种人源单克隆抗体（Fab）能特异性结合人类免疫缺陷病毒1型跨膜蛋白gp41的一个主要表位，其三维结构已通过晶体学方法测定，分辨率达2.7埃。此前已确定该抗体识别表位SGKLICTTAVPWNAS，属于IgG1（κ）亚类，并具有抗体依赖性细胞毒性。Fab的四级结构呈伸展构象，恒定区和可变区之间的肘弯角为175度。在结构上，四个高变环可根据先前公认的典型结构进行分类。重链（H3）和轻链（L3）的第三个高变环在结构上有所不同。高变环H3（残基102H - 109H）异常地从表面伸展出来。互补决定区形成一个疏水结合口袋，主要由高变环L3、H3和H2构成。
