The primary interest of the Limbach Group is to develop new and improved mass spectrometric methods to characterize RNAs and RNPs. As such, we have active research programs involved in nucleic acid analysis by mass spectrometry; structural biology and medical applications. Below you will find more detail on each of our specific areas of research. If you have any questions or would like to discuss our research program, please contact me via phone (513-556-1871), fax (513-556-9239) or email (Pat.Limbach@uc.edu).

Structural Characterization of Nucleic Acids

Mass spectrometry is now capable of analyzing intact nucleic acids with mass accuracies of 99.99% or better! This development has opened up a new field of analysis in nucleic acids. One of the main areas of our research is the use of high resolution mass spectrometry to help elucidate structure-function relationships in ribonucleic acids (RNAs). Messenger RNA (mRNA), transfer RNA (tRNA) and ribosomal RNA (rRNA) are all present in the ribosome and participate in protein synthesis. It has been discovered that these RNAs contain modified nucleosides. We are interested in identifying these modifications and determining their role in protein synthesis.

Another interest in our lab is to develop mass spectrometry-based assays for the characterization and quantification of mixtures of small RNAs, such as microRNAs and tRNAs. By combining isotopic-labeling strategies with unique "signature" endonuclease digestion products, we are able to both identify and quantify complex mixtures of RNAs without resorting to time-consuming separation methods. These assays allow us to focus on new strategies of significance in medically related fields.

Structural Biology

Our work here focuses on the use of MALDI-MS and (tandem)-LC-ESI-MS/MS to characterize proteins and RNAs isolated from a variety of ribonucleoprotein complexes (RNPs). In particular, we working on the development of new approaches for characterizing protein-nucleic acid sites of interaction by analysis of cross-linked products.

Medical Applications

With new assays, methods and strategies in place that facilitate the characterization of RNAs and RNPs, our newest efforts have included research within areas of medical importance. Examples include a focus on higher throughput screening methods for identifying modified or mutated microRNAs and tRNAs, especially those smaller RNAs known or suspected to be pathologically significant.