生物谷报道：如果你已经厌倦了发烧时将体温计含在嘴来量体温，那么你或许可以选择用1种在细胞内部的“芯片实验室”，即1种闪动的蛋白质可能成为理想的体温计。
来源于生物发光水母Aequorea victoria的绿色荧光蛋白（GFP）在着少特定波长的光时会发出绿色荧光。但 是，这种怪异的光不是持续性的。在液体中，这种蛋白质在丧失质子和得回质子时，出现光的明暗闪烁。
现在，来自加拿大McMaster大学的Cécile Fradin和同事发现，闪烁的频率在热的环境条件下变缓慢，而在温度降低时则加速。这个特征使它能够成为1种缩微型的体温计。
研究人员用1束光照射含有这种蛋白质的液体，然后根据荧光的闪烁频率来确定温度。他们发现在10到50摄氏度之间，这种蛋白质的闪烁频率能够准确测量所处的液体环境的温度。
绿色萤光蛋白(green fluorescent protein)，简称GFP，最早是由下村脩等人于1962年在1种学名Aequorea victoria的水母中发现。其基因所产生的蛋白质，在蓝色波长范围的光线激发下，会发出绿色荧光。这个发光 的过程中还需要冷光蛋白质Aequorin的帮助，且这个冷光蛋白质与钙离子(Ca+2)可产生交互作用。
由水母Aequorea victoria中发现的野生型绿色荧光蛋白，395nm和475nm分别是最大和次大的激发波长，它的发射波长的峰点是在509nm，在可见光绿光的范围下是较弱的位置。由海肾(sea pansy)所得的绿色荧光蛋白，仅有在498nm有1个较高的激发峰点。
在细胞生物学与分子生物学领域中，绿色荧光蛋白基因常被用作为1个报导基因(reporter gene)。1些经修饰过的型式可作为生物探针，绿色荧光蛋白基因也可以克隆到脊椎动物中。
原始出处:
J. Am. Chem. Soc., 129 (34), 10302 -10303, 2007. 10.1021/ja0715905 S0002-7863(07)01590-9
Web Release Date: August 8, 2007 Copyright ? 2007 American Chemical Society
A Molecular Thermometer Based on Fluorescent Protein Blinking
Felix H. C. Wong, Daniel S. Banks, Asmahan Abu-Arish, and Cécile Fradin*
Department of Physics and Astronomy, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4M1, and Department of Biochemistry and Biomedical Science, McMaster University, 1200 Main Street West, Hamilton, Ontario, Canada, L8N 3Z5 Received March 6, 2007
Abstract:
With the present trend toward a miniaturization of chemical systems comes the need for a precise characterization of physicochemical parameters in very small fluid volumes. We describe here an original approach for small-scale temperature measurements based on the detection of fluorescent protein blinking. We observed that the characteristic time associated with the reversible protonation reaction responsible for the blinking of the enhanced green fluorescent protein is strongly temperature dependent at low pH. The blinking characteristic time can easily be detected by fluorescence correlation spectroscopy, and therefore provides the means for noninvasive, spatially resolved, absolute temperature measurements. We applied this approach to the quantification of laser-heating effects in thin liquid samples. As expected, we observed a linear dependence between the temperature increase at the laser focus and both the laser power and the sample extinction coefficient. In addition, we were able to measure the laser induced temperature increase at the glass/liquid interface, a value difficult to predict and hard to access experimentally, demonstrating the usefulness of our approach to study surface effects in microfluidic chips. The use of GFP derivatives as genetically encoded molecular thermometers should have direct applications for both microfluidics and single-cell calorimetry.
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