The studies in this lab on the enzyme system of respiratory chain were reviewed briefly. Two inhibitors which affect simultaneously on three Q-related enzymes of complex Ⅰ.Ⅱ and N were synthesized. They could be an useful tools in the studies of ubiquinone reactions in respiratory chain. The direct interaction between TTFA inhibitive site of QH→QH₂ of complex Ⅱ and cytochrome b₅₆₂ of complex Ⅲ was found. This kind of interactions may playsome roles in modulating the electron transfer from complex Ⅱ to complex Ⅲ. The maximum reconstitutive activity of lipid-deplited succinate-cytochrome c reductase with mixed phospholipids PC:CL:PE=2:2:1 were obtained. this means not only the lipid but also thier composition were important for regulating the enzyme activiy of respiratory chain.