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Substrate-assisted laser desorption of neutral peptide molecules
1Department of Chemistry, University of Georgia, Athens 30602.
Analytical Chemistry
|May 1, 1992
Summary
Using sinapinic acid as a substrate enhances ultraviolet laser desorption of intact neutral peptide molecules. This method reduces internal energy, improving peptide analysis with laser desorption/chemical ionization Fourier transform mass spectrometry.
Area of Science:
- Analytical Chemistry
- Biochemistry
- Physical Chemistry
Background:
- Laser desorption is a key technique for analyzing biomolecules like peptides.
- Optimizing desorption conditions is crucial for preserving molecular integrity and reducing internal energy.
- Current methods face challenges in efficiently desorbing intact neutral peptides, especially larger ones.
Purpose of the Study:
- To investigate the effect of an ultraviolet-absorbing organic substrate on laser desorption of neutral peptide molecules.
- To determine if this substrate enhances the desorption of intact neutral peptides at 248 nm.
- To compare the internal energy of desorbed neutrals prepared with the substrate versus traditional methods.
Main Methods:
- Sample preparation involved depositing peptides (up to gramicidin S) as a thin layer (500 monolayers) on a sinapinic acid substrate.
- Laser desorption at 248 nm was used to desorb neutral peptide molecules.
- Analysis was performed using laser desorption/chemical ionization (LD/CI) Fourier transform mass spectrometry.
Main Results:
- The use of a sinapinic acid substrate significantly enhanced the desorption of intact neutral peptide molecules at 248 nm.
- Peptides as large as gramicidin S were successfully desorbed as intact neutrals.
- Desorbed neutrals exhibited approximately 1 eV less internal energy compared to those desorbed from a metal film.
- The substrate's effectiveness was dependent on laser wavelength, aiding desorption at 248 nm but not at 193 nm (where peptides absorb strongly).
Conclusions:
- Sinapinic acid serves as an effective matrix or substrate to promote the desorption of intact neutral peptides via 248 nm laser irradiation.
- This substrate-assisted laser desorption technique offers a method to reduce the internal energy of desorbed neutrals, beneficial for mass spectrometry.
- The findings highlight the importance of substrate-laser wavelength compatibility for optimizing neutral molecule desorption.
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