Richard M. Caprioli, PhD, is a Professor of Biochemistry at Vanderbilt University School of Medicine. His research interests are aimed at the investigation of biological processes involving the synthesis, modification, storage and degradation of certain peptides and proteins using modern mass spectrometric methods of analysis to follow molecular events.
In recent years there has been a great amount of interest in investigating the biochemical events involved in the metabolism of peptides, primarily in the brain and gut of mammals, encompassing the enzymatic breakdown of these peptides, their production from peptide and protein precursors, and the disruption of these processes by certain xenobiotics. Modern mass spectrometric techniques are used in these studies, including electrospray and matrix-assisted laser desorption ionization mass spectrometry. This research is generally carried out with two experimental approaches.
The first involves in vivo metabolic studies in live animals (rats) using microdialysis sampling procedures together with molecular identification and quantitation by electrospray tandem mass spectrometry. The second experimental approach used in the study of cellular peptide metabolism utilizes new molecular imaging technology that is being developed in our lab. This method involves molecular mapping of animal tissue through the production of ion images obtained from the analysis of mammalian tissue slices by matrix-assisted laser desorption mass spectrometry (MALDI MS)12. This technique permits a tissue section to be mapped in multiple molecular weight values, localizing the molecules in an X, Y coordinate representation of the sample. Ion images are produced by repetitive exposure of the sample to the laser beam, where adjacent spots are irradiated, resulting in an ordered array of mass spectra that are keyed to specific locations in the sample.