The dependence of the rate of oxygen uptake upon the ubiquinone (Q)-pool reduction level in mitochondria isolated during the development of thermogenesis of Arum maculatum spadices has been investigated. At the α-stage of development, the respiratory rate was linearly dependent upon the reduction level of the Q-pool (Qr) both under state-3 and -4 conditions. Progression through the β/γ to the Δ-stage resulted in a non-linear dependence of the state-4 rate on Qr. In the Δ-stage of development, both state-3 and -4 respiratory rates were linearly dependent upon Qr due to a shift in the engagement of the alternative oxidase to lower levels of Qr. Western blot analysis revealed that increased alternative oxidase activity could be correlated with expression of a 35 kDa protein. Respiratory control was only observed with mitochondria in the α-stage of development. At the β/γ-stage of development, the addition of ADP resulted in a significant oxidation of the Q-pool which was accompanied by a decrease in the respiratory rate. This was due either to decreased contribution of the alternative pathway to the overall respiratory rate under state 3 or by deactivation of succinate dehydrogenase activity by ADP. Cold-storage of the spadices at the β-stage of development led to increased activity of both the cytochrome pathway and succinate dehydrogenase, without any change in alternative oxidase activity. Results are discussed in terms of how changes in the activation level of the alternative oxidase and succinate dehydrogenase influence the activity and engagement of the quinol-oxidizing pathways during the development of thermogenesis in A. maculatum.
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July 1996
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Research Article|
July 01 1996
Kinetic analysis of the mitochondrial quinol-oxidizing enzymes during development of thermogenesis in Arum maculatum L
Graeme R. LEACH;
Graeme R. LEACH
*Biochemistry Department, University of Sussex, Falmer, Brighton, BN1 9QG, U.K.
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Klaas KRAB;
Klaas KRAB
†Department of Molecular and Cellular Biology, Vrije Universiteit, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
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David G. WHITEHOUSE;
David G. WHITEHOUSE
*Biochemistry Department, University of Sussex, Falmer, Brighton, BN1 9QG, U.K.
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Anthony L. MOORE
Anthony L. MOORE
‡
*Biochemistry Department, University of Sussex, Falmer, Brighton, BN1 9QG, U.K.
‡To whom correspondence should be addressed.
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Publisher: Portland Press Ltd
Received:
January 25 1996
Revision Received:
March 04 1996
Accepted:
March 11 1996
Online ISSN: 1470-8728
Print ISSN: 0264-6021
The Biochemical Society, London © 1996
1996
Biochem J (1996) 317 (1): 313–319.
Article history
Received:
January 25 1996
Revision Received:
March 04 1996
Accepted:
March 11 1996
Citation
Graeme R. LEACH, Klaas KRAB, David G. WHITEHOUSE, Anthony L. MOORE; Kinetic analysis of the mitochondrial quinol-oxidizing enzymes during development of thermogenesis in Arum maculatum L. Biochem J 1 July 1996; 317 (1): 313–319. doi: https://doi.org/10.1042/bj3170313
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