Publications (4)27.98 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Identification of bacteria: A methoxyimino cephalosporin derivative containing a pair of fluorescence resonance energy transfer (FRET) fluorophores was synthesized. This probe displays selective cleavage toward different types of β-lactamases, thereby providing a rapid assay to distinguish bacterial cells that are either sensitive or resistant to broad-spectrum β-lactam antibiotics.
- [Show abstract] [Hide abstract] ABSTRACT: Intracellular amine metabolite changes were quantified from hyperglycemic human aortic endothelial cells (HAECs) as a model for macrovascular complications of diabetes. Amines were selectively tagged using the N-hydroxysuccinimide ester (NHS) based isobaric tag DiART (Deuterium isobaric Amine Reactive Tag), synthesized in house. DiART labeling improved chromatographic resolution of derivatized amines, resulted in 100-fold signal-to-noise enhancement in mass spectrometry (MS) analyses, and allowed multiplex quantification of four samples concurrently through tandem MS fragmentation. Targeted measurement of 31 DiART-tagged amines demonstrated the limits of detection below 10 nM/100 amol and averaged RSDs less than 5%. Examination of endothelial cells exposed to short-term hyperglycemia resulted in significant changes to alanine, proline, glycine, serine, and glutamine compared to osmotic controls. Discovery of proline elevation in hyperglycemic endothelial cells suggests a role of proline in hyperglycemia-mediated oxidative stress. Exposure of endothelial cells to high glucose for 7 days resulted in reduced cell number and significant changes to 21 amines relative to cell number. Prominent amine elevation from long-term hyperglycemia include aminoadipate as a sign of lysine breakdown through oxidative stress; cystathionine, hypotaurine, and proline indicating an antioxidant response; and glutamine/glutamate as substrate level activators of additional metabolic pathways. This report is the first investigation of amine changes to hyperglycemic endothelial cells and offers new insights into the pathophysiology of diabetic complications.
- [Show abstract] [Hide abstract] ABSTRACT: Protein-fragment complementation assay using a hydrolysis-deficient β-lactamase provides a robust tool for studying protein-protein interactions.
- [Show abstract] [Hide abstract] ABSTRACT: This paper demonstrates the applications of a novel isobaric reagent, named deuterium ((2)H) isobaric amine-reactive tag (DiART), for quantitative proteomics. Peptides labeled with DiART were analyzed using an electrospray ionization (ESI)-based LTQ-Orbitrap mass spectrometer. Our data showed that (2)H-associated isotope effects, such as partial loss of (2)H labels during tandem mass spectrometry (MS/MS) and (2)H-related chromatographic shift, were either not observed or negligible. With the use of a hybrid collision-induced dissociation (CID)-higher energy C-trap dissociation (HCD) acquisition method, we were able to identify DiART-labeled peptides with high confidence and quantify them with high accuracy. Furthermore, we adopted a hybrid electron-transfer dissociation (ETD)-HCD acquisition protocol and developed a novel data analysis approach to measure phosphorylation of peptides. Our results showed DiART had excellent performance on LTQ-Orbitrap instruments and provided a cost-effective technique for large-scale quantitative proteomics measurements.