Abstract
A method is presented for the preparation of pure phthalonic acid (PTA) in high yields. This PTA was used to determine the capacity of the malate/aspartate shuttle in pea (Pisum sativum) leaf mitochondria. The inhibition of glycine-dependent O2 uptake in the combined presence of 5 mM-aspartate and 5 mM-2-oxoglutarate (2-OG) was decreased by 55 +/- 22% (n = 13) in washed and 50 +/- 2% (n = 11) in purified mitochondria by 0.23 mM-PTA. This concentration of PTA had no effect on the oxidation of 5 mM-2-OG, suggesting that part of the observed inhibition of O2 uptake in the presence of aspartate and 2-OG was due to the production of oxaloacetate (OAA) by aspartate aminotransferase external to the mitochondrial inner membrane. Levels of external aspartate aminotransferase were estimated to be 24 +/- 1% (n = 4) and 13 +/- 1% (n = 4) of the total mitochondrial activity in washed and purified mitochondria respectively. Malate/aspartate-shuttle activity was estimated directly by measuring rates of malate efflux from isolated mitochondria and was found to match estimates of shuttle activity based on the PTA-insensitive inhibition of O2 uptake. Comparisons of malate/aspartate- and malate/OAA-shuttle activities indicated potentially similar rates of NADH export from pea leaf mitochondria under conditions in vivo. These extrapolated to whole-tissue rates of 5-11 mumol of NADH.h-1.mg of chlorophyll-1. The potential role of the malate/aspartate shuttle in the support of photorespiratory glycine oxidation in leaf tissue is discussed.
Full text
PDF![669](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/70c606487f37/biochemj00250-0051.png)
![670](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/17c9b9aaa27d/biochemj00250-0052.png)
![671](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/3ddcea88ef00/biochemj00250-0053.png)
![672](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/b47b2b6142f2/biochemj00250-0054.png)
![673](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/85212d9ef6ec/biochemj00250-0055.png)
![674](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/dd384f49bb61/biochemj00250-0056.png)
![675](https://cdn.ncbi.nlm.nih.gov/pmc/blobs/7d60/1148184/564345444087/biochemj00250-0057.png)
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Arnon D. I. COPPER ENZYMES IN ISOLATED CHLOROPLASTS. POLYPHENOLOXIDASE IN BETA VULGARIS. Plant Physiol. 1949 Jan;24(1):1–15. doi: 10.1104/pp.24.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Canvin D. T., Berry J. A., Badger M. R., Fock H., Osmond C. B. Oxygen exchange in leaves in the light. Plant Physiol. 1980 Aug;66(2):302–307. doi: 10.1104/pp.66.2.302. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Chevallier D., Douce R. Interactions between Mitochondria and Chloroplasts in Cells: I. Action of Cyanide and of 3-(3,4-Dichlorophenyl)-1,1-dimethylurea on the Spore of Funaria hygrometrica. Plant Physiol. 1976 Mar;57(3):400–402. doi: 10.1104/pp.57.3.400. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Day D. A. Malate Decarboxylation by Kalanchoë daigremontiana Mitochondria and Its Role in Crassulacean Acid Metabolism. Plant Physiol. 1980 Apr;65(4):675–679. doi: 10.1104/pp.65.4.675. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Day D. A., Wiskich J. T. Glycine metabolism and oxalacetate transport by pea leaf mitochondria. Plant Physiol. 1981 Aug;68(2):425–429. doi: 10.1104/pp.68.2.425. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Douce R., Moore A. L., Neuburger M. Isolation and oxidative properties of intact mitochondria isolated from spinach leaves. Plant Physiol. 1977 Oct;60(4):625–628. doi: 10.1104/pp.60.4.625. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Journet E. P., Neuburger M., Douce R. Role of Glutamate-oxaloacetate Transaminase and Malate Dehydrogenase in the Regeneration of NAD for Glycine Oxidation by Spinach leaf Mitochondria. Plant Physiol. 1981 Mar;67(3):467–469. doi: 10.1104/pp.67.3.467. [DOI] [PMC free article] [PubMed] [Google Scholar]
- LOWRY O. H., ROSEBROUGH N. J., FARR A. L., RANDALL R. J. Protein measurement with the Folin phenol reagent. J Biol Chem. 1951 Nov;193(1):265–275. [PubMed] [Google Scholar]
- Meijer A. J., von Woerkom G. M., Eggelte T. A. Phthalonic acid, an inhibitor of alpha-oxoglutarate transport in mitochondria. Biochim Biophys Acta. 1976 Apr 9;430(1):53–61. doi: 10.1016/0005-2728(76)90221-8. [DOI] [PubMed] [Google Scholar]
- Moore A. L., Jackson C., Halliwell B., Dench J. E., Hall D. O. Intramitochondrial localisation of glycine decarboxylase in spinach leaves. Biochem Biophys Res Commun. 1977 Sep 23;78(2):483–491. doi: 10.1016/0006-291x(77)90204-2. [DOI] [PubMed] [Google Scholar]
- Nash D., Wiskich J. T. Properties of substantially chlorophyll-free pea leaf mitochondria prepared by sucrose density gradient separation. Plant Physiol. 1983 Mar;71(3):627–634. doi: 10.1104/pp.71.3.627. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Oliver D. J., Walker G. H. Characterization of the transport of oxaloacetate by pea leaf mitochondria. Plant Physiol. 1984 Oct;76(2):409–413. doi: 10.1104/pp.76.2.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schmitt M. R., Edwards G. E. Provisions of reductant for the hydroxypyruvate to glycerate conversion in leaf peroxisomes : a critical evaluation of the proposed malate/aspartate shuttle. Plant Physiol. 1983 Jul;72(3):728–734. doi: 10.1104/pp.72.3.728. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de la Roche A. I. Increase in linolenic Acid is not a prerequisite for development of freezing tolerance in wheat. Plant Physiol. 1979 Jan;63(1):5–8. doi: 10.1104/pp.63.1.5. [DOI] [PMC free article] [PubMed] [Google Scholar]