Mass Spectrometer

Renne Lu, Ph.D., Senior Scientist

The mass spectrometer is an instrument for determining the mass of molecules. During the past decade, mass spectrometry has been increasingly applied to biological sciences thanks to advances in the development of matrix-assisted laser desorption ionization (MALDI) techniques, which facilitate vaporization and ionization of biological samples from a solid state into the gas phase. When a molecule carrying a positive or negative charge travels through a long tube in an electric field, its velocity depends on its charge and its mass: the smaller a mass per charge is, the faster the molecule will travel. If the time required to reach the detector at the other end of the tube is measured, the mass of the molecule can be calculated. This new type of instrument, which BBRI purchased using grants awarded by NIH and NSF, is called MALDI-TOF (time of flight) mass spectrometer.

spectrometer

The precision offered by MALDI-TOF mass spectrometry allows us to detect minute changes in the mass of a molecule. Mass spectrometry can therefore be used in a wide range of applications in research laboratories or pharmaceutical companies. Common applications include quality control of synthetic peptides and drugs, verification of proteins and protein fragments generated by recombinant DNA techniques, and identification of phosphorylation and other post-translational modifications of proteins, which are often critical for the regulation and functions of proteins.

The ability of the MALDI mass spectrometer to analyze a complex mixture and its superb sensitivity make this instrument one of the most powerful tools in proteomics during the current post-genomic era. An unknown protein may be cleaved into smaller fragments by an enzyme or chemically and the masses of the fragments in the mixture can be determined by mass spectrometry. Upon comparison of the results with information in the genomic database, the original parent protein can be unambiguously identified. This instrument also allows the identification of proteins associated with certain diseases, either up- or down-regulated, or binding partners of a molecule with known functions.

The ability of the mass spectrometer to analyze a complex mixture and its superb sensitivity make this instrument one of the most powerful tools in proteomics during the current post-genomic era.