MICROCALORIMETER MEASUREMENTS OF DNA-PROTEIN INTERACTIONS

使用各种蛋白质来改变人类免疫系统的反应 对器官移植、艾滋病和 化疗。在NCI，已经开发了几种新的蛋白质来 这就是目的。目前，这些蛋白质只有少量可用 金额。通过将这些蛋白质与精心构建的分子混合 和测量热焓，蛋白质-DNA键的相互作用可以 要下定决心。NCI和NIDDK的调查人员咨询了BEIP 关于测量这些小样本的热量。我们建议您使用 我们的钽止流微量热计，它有能力 在80微升的样品中测量10微焦耳或更小的热量。这个 最初的实验表明，我们可以测量的热量范围在5 标准误差小于0.5微焦耳的微焦耳。我们有 现在完成了对这种蛋白质的初步研究，与两种不同的 DNA的宿主温度为25摄氏度和37摄氏度。 停流微量热计，我们能够测量结合热 DNA宿主上的一个碱基对改变时的差异。结果显示 热焓很低，这表明结合几乎是 完全是由信息量驱动的。

The use of various proteins to modify the human immune system response is of intense interest in the areas of organ transplants, AIDS, and chemotherapy. At the NCI, several new proteins have been developed for this purpose. At present, these proteins are available only in small amounts. By mixing these proteins with carefully constructed molecules of DNA and measuring the enthalpy, the protein-DNA bond interactions can be determined. Investigators at the NCI and NIDDK consulted the BEIP about measuring the heats of these small samples. We recommended using our tantalum stopped-flow microcalorimeter, which has the capability of measuring heats of 10 microjoules or less in 80-microliter samples. The first experiments showed that we could measure heats in the range of 5 microjoules with a standard error of less than 0.5 microjoules. We have now completed the preliminary study of this protein with two different DNA hosts at 25 degrees and 37 degrees C. Using the tantalum stopped-flow microcalorimeter, we were able to measure a binding heat difference when one base pair on the DNA host was changed. Results show that the enthalpy is very low, which indicates that the binding is almost exclusively entropy-driven.