It is often assumed that most proteins turnover rapidly within biology, but recent results have demonstrated that many proteins can reside in cells for surprising amounts of time, weeks, months, or even years! As these long-lived proteins sit around, inevitably bad things start to happen, including truncation, oxidation, isomerization, deamidation, and epimerization. These are all spontaneous chemical modifications that are not under enzymatic control and can have serious consequences on protein properties and function. Many of these modifications are difficult to detect, for example isomerization leads to a subtle structural change and no shift in mass. The Julian lab specializes in identifying spontaneous chemical modifications, including those most difficult to detect, and investigating the biological consequences of those modifications in various pathways within biology. We rely on mass spectrometry, photochemistry, confocal microscopy, and other methods to carry out these experiments. In particular, we are interested in studying long-lived proteins within post-mitotic cells where the effects of aging lead to many well-known diseases including Alzheimer's disease, macular degeneration, and cardiomyopathy.