Mass spectrometric and biological characterization of guinea-pig corticotrophin

SwePep, a database designed for endogenous peptides and mass spectrometry

A new database, SwePep, specifically designed for endogenous peptides, has been constructed to significantly speed up the identification process from complex tissue samples utilizing mass spectrometry. In the identification process the experimental peptide masses are compared with the peptide masses stored in the database both with and without possible post-translational modifications. This intermediate identification step is fast and singles out peptides that are potential endogenous peptides and can later be confirmed with tandem mass spectrometry data. Successful applications of this methodology are presented. The SwePep database is a relational database developed using MySql and Java. The database contains 4180 annotated endogenous peptides from different tissues originating from 394 different species as well as 50 novel peptides from brain tissue identified in our laboratory. Information about the peptides, including mass, isoelectric point, sequence, and precursor protein, is also stored in the database. This new approach holds great potential for removing the bottleneck that occurs during the identification process in the field of peptidomics. The SwePep database is available to the public.

Peptidomics-based discovery of novel neuropeptides

Modern proteomic methodologies have significantly improved the possibilities of large-scale identification of proteins. However, these methodologies are limited by their inability to reliably detect endogenously expressed peptides. We describe a novel approach of combining sample preparation, comprising focused microwave irradiation and mass spectrometric peptide profiling that has enabled us to simultaneously detect more than 550 endogenous neuropeptides in 1 mg of hypothalamic extracts. Automatic switching tandem mass spectrometry and amino acid sequence determination of the peptides showed that they consist of both novel and previously described neuropeptides. The methodology includes virtual visualization of the peptides as two- and three-dimensional image maps. In addition, several novel and known post-translational modifications of the neuropeptides were identified. The peptidomic approach proved to be a powerful method for investigating endogenous peptides and their post-translational modifications in complex tissues such as the brain. It is anticipated that this approach will complement proteomic methods in the future.

Mass spectrometry of peptides in neuroscience

This review focuses on the contributions of modern mass spectrometry to neuropeptide research. An introduction to newer mass spectrometric techniques is provided. Also, the use of mass spectrometry in combination with high-resolution separation techniques for neuropeptide identification in biological samples is illustrated. The amino acid sequence information that is important for the identification and analysis of known, novel, or chemically modified neuropeptides may be obtained using mass spectrometric techniques. Because mass spectrometry techniques can be used to reflect the dynamic properties associated with neuropeptide processing in biological systems, they may be used in the future to monitor peptide profiles within organisms in response to environmental challenges such as disease and stress.