... (2-methyl-1,4-naphthoquinone), and duroqui-none (tetramethyl-p-benzoquinone) were purchased fromAldrich. Juglone (5-hydroxy-1,4-naphthoquinone), plumb-agin (5-hydroxy 2-methyl-1,4-naphthoquinone), coen-zyme Q0(2,3-dimethyl ... analogue 2-n-heptyl- 4- hydroxyquinoline-N-oxide (HOQNO) in the medium inhib-its reduction of the cytochrome by menadiol, but does notinhibit reduction by duroquinol (Fig. 3). It is probable that the ... single quinol-binding site. However, the technique used to determine binding sites of quinols,inhibition by HOQNO (a structural analogue of menaqui-none), did not allow them to see the binding...