A complete system for quantifying complex I inhibition.

• Measure complex I activity in isolated mitochondria
• Useful for screening compounds for complex I inhibition
• Suitable for high-throughput screening
• Plate-based colorimetric measurement (340 nm)
• MitoCheck® Mitochondrial (Tissue) Isolation Kit is available to aid in mitochondrial tissue isolation

Complex I (NADH oxidase/Co-enzyme Q reductase) is one of the major sites of electron entry into the mitochondrial electron transport chain (ETC). Complex I catalyzes the 2 electron oxidation of NADH followed by the reduction of ubiquinone (Q) to form ubiquinol (QH₂), and ultimately the reduction of the terminal electron acceptor, O₂. During the passage of electrons from NADH to Q, the translocation of four protons (H+) from the mitochondrial matrix to the intermembrane space occurs, contributing to the chemiosmotic proton gradient, which is required for oxidative phosphorylation. Cayman's MitoCheck® Complex I Activity Assay allows for the activity of complex I to be determined without the need to isolate mitochondria or pre-incubate with antibodies. The rate of NADH oxidation is measured by a decrease in absorbance at 340 nm and is proportional to the activity of complex I.