Respiratory complex I is a multi-subunit membrane protein complex that reversibly couples NADH oxidation and ubiquinone reduction with proton translocation against transmembrane potential. Complex I from Escherichia coli is among the best functionally characterized complexes. but its structure remains unknown. hindering further studies to understand the enzyme coupling mechanism. https://www.diegojavierfares.com/flash-choice-Little-Mermaid-Ariel-Girls-Purple-Costume-Tiara-amazing-save/