Mitochondrial Complex I or NADH: ubiquinone oxidoreductase is the first and the largest complex of the electron transport chain located in the mitochondrial membrane. It oxidizes NADH to NAD+ and transfers an electron to ubiquinone (also present in the inner mitochondrial membrane) converting it to ubiquinol. During this process, it transports protons across the inner mitochondrial membrane, helping to develop an electrochemical gradient. This process is very important for cellular respiration and adverse effects on Complex I activity can compromise mitochondrial respiration, which further leads to cellular stress.
This kit uses decylubiquinone, an analog of ubiquinone, as an electron acceptor that gets converted to decylubiquinol through the catalytic activity of Complex I. Complex I activity is determined by recording the change in absorbance (A600) of the reduced Complex I dye. Specific Complex I activity is obtained by subtracting the activity in presence of Complex I inhibitor rotenone from total activity. This kit can detect as low as 0.1 mU/well and is linear up to 7 mU/well.
Rosa, J. B., Kim, H. H., Luong, J., Yang, J., Yee, P., Yan, A., Rodriguez, A., & Kayser, M. S. (2026). Reverse electron transfer at mitochondrial complex I restrains dopaminergic neuron activity to promote early-life sleep in Drosophila. bioRxiv. https://doi.org/10.64898/2026.02.22.707308
