Deubiquitinating enzyme(DUBs) is an enzyme that regulates ubiquitin-dependent metabolic pathways.Deubiquitinating enzymes are a large group of proteins that cleave ubiquitin-protein bonds. Potentially, DUBs may act as negative and positive regulators of the ubiquitin system. In addition to ubiquitin recylcing, they are involved in processing of ubiquitin precursors, in proofreading of protein ubiquitination and in disassembly of inhibitory ubiquitin chains. Ribbon diagram of the catalytically perfect enzyme TIM. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. ... // The protein Ubiquitin is a small protein that occurs in all eukaryotic cells. ...