Professor of Chemistry, University of Massachusetts
Ph.D.: University of North Carolina, Chapel Hill
Proteins are essential players in most biological processes and unraveling their behavior (or misbehavior) is important for understanding the molecular basis of life and of a variety of diseases. My research group is interested in protein chemistry with a particular focus on the development of new methods to gather insight into protein misfolding and aggregation, protein interactions with metals, and protein chemistry within a cell. We have two primary areas of investigation: (1) mass spectrometry-based methods to study protein amyloid formation and (2) nanomaterials as novel extraction/concentration/detection methods for protein analyses in complex mixtures.
An increasing number of proteins are known to form amyloid fibrils in vivo, and the formation of these fibrils is implicated in several diseases (e.g. Alzheimer’s, Parkinson’s). One of these proteins, β-2-microglobulin (β2m), can form amyloid fibrils, and these fibrils are the main pathogenic process underlying dialysis-related amyloidosis (DRA). Like other amyloid systems, β2m fibril formation proceeds by partial protein unfolding, subsequent oligomerization, and eventual elongation to form mature fibrils. While aspects of general amyloid formation are understood, molecular-level information about the early stages of the amyloid reaction is lacking for almost all amyloid systems; however, this information is critical for the rational design of therapeutics against amyloid diseases. We strive to obtain amino acid-level information of the unfolding and oligomerization of β2m prior to fibril formation by developing mass spectrometry-based methods with the necessary temporal and spatial resolution. We are particularly interested in the role that Cu(II) plays in the amyloid formation of β2m. In general, the methods that we develop not only provide insight into β2m’s amyloidosis but are also general enough to work for other amyloid systems.
Nanomaterials have great potential for enhancing protein analysis in complex mixtures. We use functionalized nanomaterials as new extraction/concentration/detection methods that can more fully exploit the exquisite sensitivity and specificity of mass spectrometry. The “bottom-up” design control of these materials from the molecular level to the micron/millimeter level makes them adaptable tools for coupling with mass spectrometry. Together with mass spectrometry, these nanomaterials are being used in several contexts: (1) to extract proteins and peptides in complex mixtures with high selectivity and efficiency; (2) to fractionate protein and peptide mixtures according to desired chemical or physical properties; (3) to facilitate protein identification in complex mixtures; and (4) to detect compounds of interest in cell lysates and whole cells.
We are also developing new mass spectrometry-based approaches to track, measure, and image nanoparticles in complex samples. These methods have two particular applications. First, nanomaterials are more and more found in commercial products, and their widespread use is starting to raise concerns about their impact on the environment. Second, nanoparticles are increasingly being investigated as therapeutic delivery agents, and effective development of such delivery agents requires the ability to monitor nanoparticles in cells, tissues and/or organs. New measurement tools are therefore needed to understand the fate, transport, and bioavailability of such engineered nanoparticles.
Zhu, Z.-J.; Posati, T.; Moyano, D. F.; Tang, R.; Yan, B.; Vachet, R. W.; Rotello, V. M. “Effect of Serum Proteins on the Cellular Uptake of Gold Nanoparticles,” Small, 2012, in press.
Zhu, Z.-J.; Tang, R.; Yeh, Y.-C.; Miranda, O. R.; Yan, B.; Rotello, V. M.; Vachet, R. W. “Determination of the Intracellular Stability of Gold Nanoparticle Monolayers using Mass Spectrometry,” Anal. Chem., 2012, 2012, 84, 4321-4326.
Creran, B.; Yan, B.; Moyano, D. F.; Gilbert, M. M.; Vachet, R. W.; Rotello, V. M. “Laser Desorption Ionization Mass Spectrometric Imaging of Mass Barcoded Gold Nanoparticles for Security Applications,” Chem. Comm., 2012, 48, 4543-4545.
Zhou, Y.; Vachet, R. W. “Diethylpyrocarbonate Labeling for the Structural Analysis of Proteins: Label Scrambling in Solution and How to Avoid it,” J. Am. Soc. Mass Spectrometry, 2012, 23, 899-907.
Zhou, Y.; Vachet, R. W. “Increased Protein Structural Resolution from Diethylpyrocarbonate-based Covalent Labeling and Mass Spectrometric Detection,” J. Am. Soc. Mass Spectrometry, 2012, 23, 708-717.
Rodthongkum, N.; Ramireddy, R.; Thayumanavan, S.; Vachet, R. W. “Selective Enrichment and Sensitive Detection of Peptide and Protein Biomarkers in Human Serum Using Polymeric Reverse Micelles and MALDI-MS,” Analyst, 2012, 137, 1024-1030.
Dong, J.; Vachet, R. W. “Coordination Sphere Tuning of the Electron Transfer Dissociation Behavior of Cu(II)-Peptide Complexes,” J. Am. Soc. Mass Spectrometry, 2012, 23, 321-329.