蛋白质中DSC测试阶段含量检测方案(差示扫描量热)

M144 How Much Protein is Required for a DSC Scan? Christin T. Choma TA Instruments， 109 Lukens Drive， New Castle， DE 19720，USA etermining the thermodynamic parameters ofDa protein by differential scanning calorimetry(DSC) using the CSC Nano-DSC III requiresabout the same amount of protein as surfaceplasmon resonance or fluorescence studies. Becauseof the Nano-DSC III's extreme sensitivity and baselinereproducibility， and the sample cell's small volume(300 pL) and capillary configuration (which delaysthe onset of irreversible protein aggregation andprecipitation)， a complete， interpretable， accuratescan can be obtained on essentially any protein ofinterest. The sensitivity and accuracy of the Nano-DSCIll is demonstrated by the following data set. Henegg white lysozyme (in pH 4.0 glycine buffer) wasprepared at various concentrations (concentrations (400 pg-2 pg per scan.) established by A2go followed by serial dilutions) andscanned at 2 C/min. A single unsmoothed scan ateach concentration is shown in Figure 1. Each data set was analyzed for calorimetricenthalpy (AH)and entropy(AS)，and the van’t HoffT and AH： Lysozyme incell (pg) Calorimetric van’t Hoff AH (kJ mol') AS (kJK'mol') T(℃) AH (kJ mol') 400 512 1.46 78.0 515 100 512 1.46 78.0 509 50 517 1.47 77.9 513 25 513 1.46 77.8 513 10 515 1.47 78.0 515 5 490 1.40 78.1 510 2 503 1.43 77.8 499 Even 2 pg of lysozyme in the capillary cell is sufficientto provide quality data yielding accurate values of allfour thermodynamic parameters. Using the CSC Nano-DSCIII， precise and completethermodynamic analysis of proteins available inonly very limited quantities is now possible. Determining the thermodynamic parameters of a protein by differential scanning calorimetry (DSC) using the CSC Nano-DSC III requires about the same amount of protein as surface plasmon resonance or fluorescence studies. Because of the Nano-DSC III’s extreme sensitivity and baseline reproducibility, and the sample cell’s small volume (300 μL) and capillary configuration (which delays the onset of irreversible protein aggregation and precipitation), a complete, interpretable, accurate scan can be obtained on essentially any protein of interest.