SPECIFICITY AND COMPLEMENT BINDING EFFECT OF ANTIGEN-ANTIBODY INTERACTION

众所周知，抗原的单个氨基酸取代 决定簇显著降低了对抗体的亲和力。 这一现象与我们之前的观测结果惊人地相似 在马的三片段复合物的氨基酸取代中， 细胞色素c。 正如另一份报告所述，我们假设， 由接触基团介导的四个闭环， 离域相互作用产生额外的能量来稳定 细胞色素c和作为其一部分氨基酸的取代 会破坏离域相互作用。 到 研究一种特异性识别的氨基酸是否是 在界面上或界面内形成的假想闭合回路 在抗原和抗体之间，我们已经分离出7个单克隆抗体， 如所述的酵母全-或脱辅基-异-L-细胞色素C的抗体 在前几年。 在目前的研究中，我们有 定量测定了这些单克隆抗体与 关于酵母全-和脱辅基-异-L-细胞色素C， 进化上相关的细胞色素c，脱辅基细胞色素c， 同源和杂交片段复合物。 取得的结果 加上之前的数据，我们可以确定 具体识别的氨基酸如下。 IgG单克隆抗体： 4-74-6、Leu 63（酵母编号）和/或Asn 67和/或Asn 68; 126-6，Glu 93; 4-145-10，Thr 74; 2-96-12，Asp 65; 2-34-19，Lys 59; 和10-28-86，三甲基-赖氨酸77。 IgM单克隆抗体39-14、Pro 30和 他31岁。 除了mAb 4-14-10和39-14之外，这些mAb 单克隆抗体具有高亲和力。 使用mAb 4-126-6计算 其中Glu 93被丙氨酸取代导致 10，000倍的亲和力似乎表明， 传统的相互作用如静电（或氢 键）、疏水相互作用和货车范德华相互作用 不能完全解释亲和力的降低。因此，我们建议 一些新的，额外的原子间相互作用敏感， 原子团构型的差异可能涉及 通过闭合相互作用环预测的抗原识别 假说.

It is well known that single amino acid substitution of antigenic determinants dramatically decreases the affinity to antibodies. This phenomenon is strikingly similar to our previous observations in amino acid substitution of the three-fragment complex of horse cytochrome c. As described in another report, we hypothesize that four closed loops consisting of contacting groups mediates delocalized interaction to generate extra energy to stabilize cytochrome c and that substitution of an amino acid which is a part of this closed loop would disrupt delocalized interaction. To investigate whether a specifically recognized amino acid is a part of a hypothetical closed loop formed across or within the interface between an antigen and an antibody we have isolated 7 monoclonal antibodies to yeast holo- or apo-iso-l-cytochrome c as described in the previous years. In the present studies, we have quantitatively determined the affinities of these monoclonals with respect to yeast holo- and apo-iso-l-cytochrome c a panel of evolutionarily related cytochromes c, apocytochromes c, and homologous and hybrid fragment complexes. The results taken together with the previous data have permitted us to assign specifically recognized amino acids as follows. IgG monoclonals: 4-74-6, Leu 63 (yeast numbering) and/or Asn 67 and/or Asn 68; 4- 126-6, Glu 93; 4-145-10, Thr 74; 2-96-12, Asp 65; 2-34-19, Lys 59; and 10-28-86, trimethyl-Lys 77. IgM monoclonal 39-14, Pro 30 and His 31. With the exception of mAbs 4-14-10 and 39-14 these monoclonals are of high affinity. A calculation with mAb 4-126-6 in which replacement of Glu 93 by alanine results in a decrease in affinity by a factor of 10,000 appears to show that the sum or conventional interactions such as electrostatics (or hydrogen bond), hydrophobic interaction and van der Waals interaction does not totally account for the decrease in affinity. Thus, we suggest that some new, extra interatomic interaction sensitive to differences in configurations of atomic groups may be involved in antigen recognition as predicted by the closed interaction loop hypothesis.