Inhibitory Effects of Lower Aliphatic Alcohols on Electron Transport Phosphorylation Systems. 1. Straight-Chain, Primary Alcohols.

Publisher Website
Google Scholar
Abstract
Photophosphorylation in isolated spinach chloroplasts and chromatophores from the photo-synthetic bacterium Rhodospirillum rubrum and respiration and phosphate uptake in isolated rat liver mitochondria were found to be strongly inhibited by lower aliphatic alcohols in rather high concentrations. The inhibitory effects increased with the chain-length of the alcohol. A comparison of the sensitivity of systems with different electron transport pathways in the chromatophores and in the chloroplasts showed that similar alcohol concentrations were always required for inhibition of photophosphorylation. In the one non-cyclic photophosphorylation system tested, namely chloroplasts with electron transport from water to ferricyanide, both electron transport and phosphate esterification were shown to be inhibited. The alcohols had stronger inhibitory effects on respiration and phosphorylation in mitochondria with NAD-linked substrates such as [beta]-hydroxybutyrate and glutamate than with succinate. With the NAD-linked substrates the respiration and phosphorylation rates decreased about simultaneously, i.e. with little change in P/O ratio when the concentration of alcohol was increased, but with succinate the phosphorylation was uncoupled from respiration. Thus, of the mitochondrial functions tested, NAD-linked electron transport was most sensitive to the alcohols, presumably due to depletion of intra-mitochondrial NAD. This interpretation is supported by the demonstration that the sensitivity of the electron transport towards alcohol was considerably lowered in a system with externally added NAD.