Cytochrome Components & Electron Transfer in Sweet Potato Mitochondria.

Studies of sweet potato (Ipomioca batatas. Poir) mitochondria were extended, in our present investigation, to include spectrophotometric observation of cytochromes in response to substrates and inhibitors. These studies were facilitated by the use of a white variety of sweet potato (var. Pelican Processor which is low in carotenoids, and by the use of a nodlified Perkin-Elmer Spectracord. Cytochrome spectra xvere also obtained at liquid nitrogen temperature. WVe used a preparation showing good P /O ratios, no cytochrome c requirement, and a degree of respiratory control by ADP2 (2-fold stimulation by ADP). Observations on the mitochondrial respiratory chain, made by manometric and spectrophotometric methods. were integrated. Electron transfer in this system was relatively insensitive to respiratory-chain inhibitors. This phenomenon has been the subject of intensive investigations in a number of plant systems ( 2, 3, 5, 8, 10, 13, 14, 15, 16, 17, 22, 25, 27, 28 ). It is hoped that our results will add some insight into the l)roblem of inhibitor-resistant respiration, and increase our understanding of the cytochrome components in plant mitochonldria.