This award continues support of Tandem Mass Spectrometry activities at the Mid Atlantic Mass Spectrometry (MAMS) laboratory at the University of Maryland Baltimore County (UMBC). One of several approaches to mass spectrometry (MS), tandem MS provides high resolution measurements of compounds with the high molecular weights typical of proteins, nucleic acids and other biopolymers. Efforts sponsored by this award will focus on improving techniques for analysis of proteins and peptides using the tandem instrument; a variety of collaborative research projects will be initiated or continued. Mass spectrometry plays an increasingly important role in the structural analysis of biomolecules. Information about protein sequence and structure, including naturally occurring modifications of proteins, and similar kinds of information about polysaccharides and other branched chain polymers are obtained with great difficulty by other techniques. The MAMS laboratory includes facilities at UMBC and at The Johns Hopkins University School of Medicine. Both were established as shared instrument resources for collaborative and service projects. Because of the considerable expense of acquisition and operation of tandem MS instruments, this type of analysis is not routinely available at most research institutions. The UMBC facility provides the research community at UMBC and at numerous other institutions with access to the kind of skilled mass spectrometry needed in many areas of modern biological research.