The glycation of ubiquitin with ribose 5-phosphate (R5P) and glucose was studied to determine the effect of post-translationally modified ubiquitin on intracellular proteolysis. Our investigations focused on identifying the location of glycation sites on the ubiquitin protein and on developing a method for assessing the effect that glycation has on ubiquitin activity. A novel method which employs yeast cytochrome c as a ubiquitination target substrate and LC-MS for subsequent analysis is under development for use in assessing the functionality of modified ubiquitin. Preliminary results suggest that this is a robust method for the detection of ubiquitination. Further refinement of this method is necessary before the effects of glycation on ubiquitination can be analyzed.