Lopez Mayorga O, Freire E
Biophys Chem. 1987 Jul;27(1):87-96. doi: 10.1016/0301-4622(87)80049-2.
The apparent heat capacity function measured by high-sensitivity differential scanning calorimetry contains dynamic components of two different origins: (1) an intrinsic component arising from the finite instrument time response; and (2) a sample component arising from the kinetics of the thermal transition under study. The intrinsic instrumental component is always present and its effect on the shape of the experimental curve depends on the magnitude of the calorimeter response time. Usually, high-sensitivity instruments exhibit characteristic time constants varying from 10 to 100 s. This slow response introduces distortions in the shape of the heat capacity function especially at fast scanning rates. In addition to this instrumental component, dynamic effects due to sample relaxation processes also contribute to the shape of the experimental heat capacity profile. Since the nature and magnitude of these effects are a function of the kinetic parameters of the transition, they can be used to obtain kinetic information. This communication presents a dynamic deconvolution technique directed to remove artificial distortions in the shape of the heat capacity function measured at any scanning rate, and to obtain a kinetic characterization of a thermally induced transition. The kinetic characterization obtained by this method allows the researcher to obtain transition relaxation times as a continuous function of temperature. This technique has been applied to the thermal unfolding of ribonuclease A and the pretransition of dipalmitoylphosphatidylcholine (DPPC). In both systems the transition relaxation times are temperature dependent. For the protein system the relaxation time is very slow below the transition temperature (approximately 30 s) and very fast above Tm (less than 1 s) in agreement with direct kinetic measurements. For the pretransition of DPPC, the relaxation time is maximal at the transition midpoint and of the order of approx. 40 s.
（1）源于仪器有限时间响应的本征成分；（2）源于所研究热转变动力学的样品成分。本征仪器成分始终存在，其对实验曲线形状的影响取决于量热计响应时间的大小。通常，高灵敏度仪器表现出特征时间常数，范围从10到100秒。这种缓慢的响应会导致热容函数形状出现失真，尤其是在快速扫描速率下。除了这种仪器成分外，样品弛豫过程引起的动态效应也会影响实验热容曲线的形状。由于这些效应的性质和大小是转变动力学参数的函数，因此可以利用它们来获取动力学信息。本文介绍了一种动态去卷积技术，旨在消除在任何扫描速率下测量的热容函数形状中的人为失真，并获得热诱导转变的动力学特征。通过这种方法获得的动力学特征使研究人员能够获得作为温度连续函数的转变弛豫时间。该技术已应用于核糖核酸酶A的热解折叠和二棕榈酰磷脂酰胆碱（DPPC）的预转变。在这两个系统中，转变弛豫时间均与温度有关。对于蛋白质系统，弛豫时间在转变温度以下非常缓慢（约30秒），在高于熔点（Tm）时非常快（小于1秒），这与直接动力学测量结果一致。对于DPPC的预转变，弛豫时间在转变中点处最大，约为40秒。
