2-Thenoyltrifluoroacetone (TTFA) is an inhibitor of respiration in animals and bacteria. In animals, TTFA binds at the quinone reduction site of succinate:ubiquinone oxidoreductase (SQR; Complex II), preventing ubiquinone from binding. It inhibits NADH fumarate reductase in bacteria. TTFA also inhibits photosystem II in plants and NADH-ubiquinone oxidoreductase of the virus Vibrio cholerae, decreasing cholera toxin production. This compound is also a chelator of metals, including lanthanum, zirconium, hafnium, and neodymium.