The Regulation of Electron Partitioning between the Cytochrome and Alternative Pathways in Soybean Cotyledon and Root Mitochondria.

Journal Article (Journal Article)

The regulation of electron partitioning between the cytochrome (Cyt) and alternative pathways in soybean (Glycine max L. cv Ransom) mitochondria in the absence of added inhibitors has been studied using the oxygen isotope fractionation technique. This regulation can depend on several factors, including the amount of alternative oxidase protein, the redox status of the alternative oxidase regulatory sulfhydryl-disulfide system, the degree of activation by [alpha]-keto acids, and the concentration and redox state of the ubiquinone pool. We studied electron partitioning onto the alternative pathway in mitochondria isolated from etiolated and light-grown cotyledons and roots to ascertain how these factors interact in different tissues. In light-grown cotyledon mitochondria there is some partitioning to the alternative pathway in state 4, which is increased dramatically by either pyruvate or dithiothreitol. In etiolated cotyledon mitochondria, the alternative pathway shows little ability to compete for electrons with the Cyt pathway under any circumstances. In root mitochondria, control of alternative pathway activity is exercised by both the ubiquinone pool and the regulatory sulfhydryl-disulfide system. In addition, oxygen isotope fractionation by the Cyt and alternative pathways in mitochondria were identical to the fractionation for the respective pathways seen in intact tissue, suggesting that residual respiration is not present in the absence of inhibitors.

Full Text

Duke Authors

Cited Authors

  • Ribas-Carbo, M; Lennon, AM; Robinson, SA; Giles, L; Berry, JA; Siedow, JN

Published Date

  • March 1997

Published In

Volume / Issue

  • 113 / 3

Start / End Page

  • 903 - 911

PubMed ID

  • 12223652

Pubmed Central ID

  • 12223652

Electronic International Standard Serial Number (EISSN)

  • 1532-2548

International Standard Serial Number (ISSN)

  • 0032-0889

Digital Object Identifier (DOI)

  • 10.1104/pp.113.3.903


  • eng