Using cytochome c to monitor electron transport and inhibition in beef heart submitochondrial particles*.

We present a two-part undergraduate laboratory exercise. In the first part, electron transport in bovine heart submitochondrial particles causing reduction of cytochrome c is monitored at 550 nm. Redox-active dyes have historically been used in most previous undergraduate laboratory exercises of this sort but do not demonstrate respiratory inhibition by antimycin A and rotenone. By using cytochrome c instead of redox-active dyes, it is possible to observe inhibition of electron transport in the presence of the aforementioned respiratory inhibitors. In the second part, students are asked to design a soluble redox chain between NADH and cytochrome c using catalytic amounts of redox-active dyes. The students are also responsible for designing the assays and control. The entire experiment can be performed in 3 h with single-beam spectrophotometers that are currently used in most undergraduate teaching laboratories. This exercise is suitable for large undergraduate classes of over 200 students and can be performed either by a single student or a student pair.