Laser Heating Nanoelectrospray Emitters for Fast Protein Melting Measurements with Mass Spectrometry.
Jacob S JordanEvan R WilliamsPublished in: Analytical chemistry (2022)
Temperature-controlled nanoelectrospray ionization has been used to measure heat-induced conformational changes of biomolecules by mass spectrometry, but long thermal equilibration times associated with heating or cooling an entire emitter limit how fast these data can be acquired. Here, the tip of a borosilicate electrospray emitter is heated using 10.6 μm light from an unfocused CO 2 laser. At 1.2 W, the solution inside the emitter tip can be heated from room temperature to a steady-state temperature of 78.2 ± 2.5 °C in less than 0.5 s and cools from 82.6 ± 0.6 °C back to room temperature within 4 s. The time required to establish a steady-state temperature is more than 100-fold faster than that required for a resistively heated emitter due to the low thermal mass. Protein unfolding curves measured as a function of laser power can be acquired in ∼40 s compared to a resistively heated apparatus that required ∼21 min to acquire similar data. Laser power is calibrated to temperature by comparisons of the average charge state of the protein cytochrome c measured with laser heating and with resistive heating. This laser heating method is applied to a three-component protein mixture to demonstrate the ability to rapidly acquire melting temperatures of proteins in mixtures. The ability to rapidly assess the thermal stabilities of multiple proteins simultaneously shows significant promise for coupling temperature-controlled electrospray ionization (ESI) to separation techniques, providing a high-throughput method for determining the effects of solution composition, drug binding, or sequence mutations on protein thermal stability.
Keyphrases
- room temperature
- mass spectrometry
- high resolution
- liquid chromatography
- protein protein
- ionic liquid
- high throughput
- amino acid
- high speed
- binding protein
- electronic health record
- big data
- ms ms
- single molecule
- light emitting
- high performance liquid chromatography
- drug induced
- diabetic rats
- simultaneous determination
- solid phase extraction