The Encounter Complex in Antibody-Antigen Reactions

生物大分子之间的分子识别通常被认为是通过一种被称为“相遇复合体”的瞬时中间体发生的。在这个复合体中，两个反应物接近并反复碰撞。它们不一定彼此形成键，但不容易逃逸，因为它们被溶剂相互堆积在一起。研究人员的长期目标是开发实验方法来研究相遇复合体。研究人员提出了一种将相遇复杂的形成分解为组成步骤的方法，并将该方法应用于抗体对抗原的识别。该方法是构建同一抗体的单价和二价版本，并测量它们与抗原结合的动力学。一个结合位点的缺失会导致反应速度不足，从而影响与抗原的特定相互作用，但不会影响扩散和非特异性碰撞的一般过程。这一理论将用突变抗体和抗原进行测试，主要使用停流荧光来测量动力学。使用的模型系统将是抗原溶菌酶和人源化版本的抗溶菌酶抗体。这些研究将阐明配体-受体相互作用的新原理，这些原理是抗体和免疫系统其他分子反应性的基础。这位研究人员提出了一种分析蛋白质等复杂生物分子之间化学反应的新方法。水中的大分子在很长一段时间内平安无事地移动，然后当它们相遇时会经历一系列快速的碰撞。参与这一碰撞过程的两个分子被称为“相遇复合体”。计算机计算表明，相遇复合体是关键生命过程中的重要中介，例如抗体识别异物。研究人员计划对这一理论进行实验测试，并开发一种观察遭遇情结生物学作用的一般方法。

9807950FooteMolecular recognition between biological macromolecules is thought often to occur through a transient intermediate known as an "encounter complex". In this complex, two reactants come into proximity and collide repeatedly. They do not necessarily form bonds with each other, but cannot easily escape because they are packed against each other by solvent. The investigator's long term goal is to develop experimental approaches to study encounter complexes. The investigator proposes a method for resolving encounter complex formation into component steps, and will apply this method to antibody recognition of antigens. The method is to construct monovalent and divalent versions of the same antibody and measure the kinetics of antigen binding by each. Loss of one binding site creates a deficit in reaction rate that affects the specific interaction with antigen, but not the general processes of diffusion and non-specific collisions. This theory will be tested with mutant antibodies and antigens, using primarily stopped-flow fluorescence to measure kinetics. The model system employed will be the antigen lysozyme and a humanized version of an anti-lysozyme antibody. These studies will elucidate new principles of ligand-receptor interaction that underlie the reactivity of antibodies and other molecules of the immune system. The investigator proposes a new way of analyzing chemical reactions between complex biological molecules such as proteins. Macromolecules in water move about uneventfully for a long time, then undergo a rapid series of collisions when they meet each other. Two molecules engaged in this collision process are called an "encounter complex". Computer calculations indicate that the encounter complex is an important intermediate in crucial life processes, such as the recognition of foreign materials by antibodies. The investigator plans to test this theory experimentally, and to develop a general method of looking at the biological role of the encounter complex.