Used for the quantitative measurement of E3 ubiquitin-protein ligase activity in human biological samples such as cell lysates, tissue extracts, or serum. This ELISA kit enables researchers to monitor ubiquitination pathway dynamics, which plays a critical role in protein degradation, cell cycle regulation, DNA repair, and apoptosis. It is widely applied in cancer research, neurodegenerative disease studies (like Alzheimer's and Parkinson's), and drug development where modulation of the ubiquitin-proteasome system is a therapeutic target. The assay provides a high-throughput, sensitive, and specific method to evaluate changes in E3 ligase activity under experimental conditions or in response to pharmacological agents.