FLASH PHOTOLYSIS APPARATUS

该仪器用于测量CO结合到 不同药物处理大鼠肝微粒体细胞色素P450的变化 和致癌物质。 当CO直接加入大鼠肝微粒体时，吸光度在 450 nm发生得太快，无法在标准分光光度计上跟踪。 在 为了观察这种快速反应， 构建光解装置以监测 吸光度变化 用530 nm的激光闪光脉冲照射样品，以破坏样品的结构。 CO与P450的血红素铁之间的光不稳定键。 发送 光电倍增管检测450 nm的光。 几个光学 滤光器和透镜选择波长并聚焦光。 的 光电倍增管的电压输出被放大、滤波、输入到 模数转换器，并存储在IBM AT上。 将数据 通过最小二乘拟合多指数模型进行分析。 观察到两个动力学阶段;这些不同的观察结果表明 有两种不同类型的P450当存在底物时， 反应速率改变。

This instrument is used to measure the kinetics of CO binding to cytochromes P450 in liver microsomes from rats treated with different drugs and carcinogens. When CO is added directly to rat liver microsomes, the absorbance change at 450 nm occurs too rapidly to follow on a standard spectrophotometer. In order to observe this rapid reaction, a continuous-dye laser flash photolysis apparatus was constructed to monitor the kinetics of the absorbance change. The sample is pulsed with a laser flash at 530 nm to disrupt the photolabile bond between CO and the heme iron of the P450. Transmitted light at 450 nm is detected by the photomultiplier. Several optical filters and lenses select wavelength and focus the light. The photomultiplier voltage output is amplified, filtered, input to an analog-to-digital converter, and stored on the IBM AT. The data are analyzed by least squares fit to multiexponential models. Two kinetic phases were observed; these disparate observations indicate that there are two distinct types of P450. When substrates were present, the reaction rate changed.