A new Differential Scanning Calorimeter for the multi-user Molecular Biophysics Research Centre

差示扫描量热法(DSC)是一种重要的生物物理技术，可以用来确定蛋白质的稳定性或脂层的稳定性随温度的变化。通过在特定的“热控”隔间中逐渐提高温度，人们可以获得对蛋白质变性温度的准确估计。当配体与蛋白质结合时，蛋白质的变性温度--即蛋白质失去3D结构的点--通常会增加。这种增长的程度与互动的强度直接相关。所有商用的DSC仪器都可以以自动方式进行这些测量。因此，差示扫描量热法已成为比较各种配体，如酶底物、辅酶或辅酶、药物、药物先导、金属离子或调节化合物与纯化蛋白质结合的重要方法。在制药行业，差示扫描量热法被广泛用于研究蛋白质疗法的稳定性和筛选最佳配方条件。DSC的主要优点是它是一种完全无标签的测量：测量的参数是蛋白质展开和重新折叠时吸收(或产生)的热量。 还可以通过DSC测量直接跟踪脂类相变。近年来，人们对生物膜的主要成分磷脂进行了大量的研究。不同的磷脂双层和多层膜的相行为具有特征的转变，这种转变发生在特定的温度下，取决于其脂肪链的长度和磷脂头基的化学性质。当跨膜蛋白或干扰剂，如抗菌或抗癌肽，与这些膜模拟物结合时，相行为会改变，通常会产生不同的多肽斑块，这些斑块被选定的脂类包围，然后表现出不同的转变温度。因此，在这种情况下，无标记的DSC测量有助于表征脂质和生物膜的其他成分之间的相互作用。 为什么我们现在申请DSC仪器？2001年，我们很幸运地买到了第一台MicroCal VP-DSC仪器。该仪器一直在继续使用，多年来为我们提供了很好的服务；所取得的结果已载入许多已出版的手稿。该仪器被纳入多用户生物物理学研究中心，该中心拥有来自我们校园的所有用户。原来的DSC仪器最近发生了泄漏，制造商给我们报了一个很高的价格来修理仪器。考虑到仪器的年代(其中包括一个过时的计算机系统)，维修费用似乎过高。因此，我们决定，现在是时候用一种能够为我们提供未来15年可靠数据的新设备来取代它了。

Differential Scanning Calorimetry (DSC) is an important biophysical technique that can be used to determine the stability of proteins or the stability of lipid layers as a function of temperature. By gradually increasing the temperature in a specific ‘thermo-controlled’ compartment one can obtain an accurate estimate of the denaturation temperature of a protein. The denaturation temperature of the protein - the point where it looses its 3D structure - typically increases when ligands bind to the protein. The extent of this increase is directly related to the strength of the interaction. All commercially available DSC instruments can carry out these measurements in an automated fashion. Hence DSC has become an important method to compare the binding of various ligands, such as enzyme substrates, co-factors or co-enzymes, drugs, drug leads, metal ions or regulatory compounds to purified proteins. In the pharmaceutical industry DSC is being used extensively to study the stability of protein therapeutics and to screen for optimal formulation conditions. The main advantage of DSC is that it is a completely label-free measurement: the parameter measured is the heat that is absorbed (or produced) when proteins unfold and refold. Lipid phase transitions can also be followed directly by DSC measurements. In recent years much work has focused on studies of phospholipids, the major constituents of biological membranes. Distinct phospholipid bilayers and multilayers have characteristic transitions in their phase behaviour that occur at specific temperatures depending on the length of their fatty acid chains and the chemical nature of their phospholipid headgroups. When transmembrane proteins or perturbing agents, such as antimicrobial or anticancer peptides, are binding to these membrane mimetics, the phase behavior changes, often creating distinct patches of peptides that are surrounded by selected lipids, which then display different transition temperatures. Hence in this case the label-free DSC measurements help to characterize the interplay between the lipids and the other components of biological membranes. Why do we apply now for a DSC instrument? In 2001 we were fortunate that we could purchase our first Microcal VP-DSC instrument. The instrument has been in continued use and it has served us well over the years; the results obtained have been included in numerous published manuscripts. The instrument is incorporated in the multiuser Biophysics Research Centre, which has users from all across our campus. The original DSC instrument has recently developed a leak and the manufacturer has quoted us a steep price to have the instrument repaired. Given the age of the instrument (which includes an outdated obsolete computer system) the repair cost seems exorbitant. We have therefore decided that the time has come to replace it with a new device that can provide us with reliable data for the next 15 years.