Cyanide-insensitive Respiration

Abstract

The effect of aromatic hydroxamic acids on skunk cabbage spadix and bean hypocotyl mitochondrial respiration has been measured. It is shown that the measurement of rate versus inhibitor concentration leads to the determination of the fluxes of reducing equivalents in each of the two pathways of electron transport in both State 3 and State 4. The alternate, cyanide-insensitive pathway is regulated by the activity of the normal cytochrome pathway. The conclusions about fluxes in State 3 are confirmed by the quantitative effect of hydroxamic acids on the ADP to oxygen ratio. The alternate pathway may be involved in regulation of NADH levels in the plant cell and in heat production by the skunk cabbage spadix.