Introduction of Circular Dichroism and Stopped-Flow Spectroscopy in Chemistry Laboratories

本计画将圆二色性光谱技术及停流吸收法引入化学实验课程。 光谱学是最基本的物理测量之一，广泛应用于化学的所有领域。 然而，化学系内以前可用的光谱工具已经限制了解决诸如大分子样品内构象分布或配体结合后底物构象变化等结构问题的能力。 此外，快速混合技术的缺乏降低了溶液中快速反应（通常是半衰期为10 ms至10 s的反应）动力学研究的准确性。 新的仪器有利于检查的圆偏振光的手性系统的吸收和水溶液中的时间依赖性的现象，使用停止流动的方法的说明。 初步实验允许学生观察圆二色性对各种构象和组织变化的敏感性，并体验停流方法在溶液中检查快速反应的实用性。 这些技术的基本原理已经在该系的三个讲座课程中提出：物理化学，生物化学和生物物理化学。 新的仪器增强了现有大二物理化学实验室的动力学产品，并有助于为化学专业新批准的生物化学选项启动生物化学实验室。 该仪器还扩大了大四学生可以在所需的研究课程介绍中解决的问题范围，包括生化系统中阳离子效应的表征以及相行为对含金属液晶光学活性的影响。

This project introduces the spectroscopic techniques of circular dichroism and stopped-flow absorption methods to the chemistry laboratory curriculum. Spectroscopy is among the most fundamental of physical measurements, with extensive applications to all areas of chemistry. However, the previously available spectroscopic tools within the Chemistry Department have limited the ability to address such structural questions as the distribution of conformations within a macromolecular sample or the change in substrate conformation upon ligand binding. Furthermore, the lack of fastmixing techniques has reduced the accuracy of kinetic studies of fast reactions in solution (typically those reactions with half-lives on the order of 10 ms to 10 s). The new instrumentation facilitates the examination of the absorption of circularly polarized light by chiral systems and the elucidation of time-dependent phenomena in aqueous solution using stopped flow methods. Initial experiments allow students to observe the sensitivity of circular dichroism to a variety of conformational and organizational changes and to experience the utility of stopped-flow methods for examining fast reactions in solution. The principles underlying these techniques have already been presented in three lecture courses in the department: physical chemistry, biochemistry, and biophysical chemistry. The new instrumentation enhances the kinetic offerings in the existing sophomore physical chemistry laboratory and helps initiate a biochemistry laboratory for the newly approved biological chemistry option for chemistry majors. The instrumentation also expands the range of questions that senior majors can address in the required Introduction to Research course, including the characterization of the cation effect in biochemical systems and of the influence of phase behavior on the optical activity of metal-containing liquid crystals.