Evans 1983 Eur J Biochem: Difference between revisions
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|organism=Saccharomyces cerevisiae | |organism=Saccharomyces cerevisiae, Fungi | ||
|enzymes=Inner mt-membrane transporter | |enzymes=Inner mt-membrane transporter | ||
|topics=Ion;substrate transport, Substrate | |topics=Ion;substrate transport, Substrate | ||
|additional=Citrate, Malate, Pyruvate | |additional=Citrate, Malate, Pyruvate | ||
}} | }} |
Latest revision as of 09:20, 9 November 2016
Evans CT, Scragg AH, Ratledge C (1983) A comparative study of citrate efflux from mitochondria of oleaginous and non-oleaginous yeasts. Eur J Biochem 130:195-204. |
ยป PMID: 6825688
Evans CT, Scragg AH, Ratledge C (1983) Eur J Biochem
Abstract: Citrate efflux from mitochondria of 10 different yeasts was investigated.
- Isolated mitochondria of all the yeasts show the possession of a carrier system for dicarboxylic and tricarboxylic anions, phosphate and pyruvate.
- The tricarboxylate carrier is also specific for l-malate in all 10 yeasts.
- In citrate-loaded mitochondria, citrate efflux and l-malate uptake are directly proportional to the concentration of extramitochondrial l-malate until the translocator becomes saturated (> 8 mM l-malate in Candida curvata D).
- Rates of citrate efflux in the presence of l-malate are linear for a period of 2 min and are approximately 2.5-times greater in oleaginous than in non-oleaginous yeasts.
- The malate-citrate translocator has a significantly lower Km for l-malate in oleaginous yeasts (โผ 4.0 mM) than in non-oleaginous yeasts (โผ 8.4 mM).
- Both pyruvate and phosphate appear to stimulate the malate-citrate exchange in mitochondria of C. curvata D.
- Oleginous yeast mitochondria contain 3โ4-times higher intramitochondrial citrate levels than non-oleaginous yeast. In all these yeasts the enzymes for synthesis and metabolism of citrate were exclusively mitochondrial, the only exception being the possession of a cytosolic ATP; citrate lyase by oleaginous yeasts.
- In metabolically active mitochondria, once the malate-citrate carrier is saturated with l-malate, efflux of citrate is directly proportional to the concentration of extramitochondrial pyruvate (as acetyl donor).
- The rates of efflux of newly synthesised citrate from metabolically active mitochondria, in the presence of saturating l-malate and pyruvate, are 6โ8-times greater in oleaginous yeasts and the citric-acid-producing yeast.
- The inhibition of aconitase by fluorocitrate produced a ninefold increase in citrate efflux from non-oleaginous yeast mitochondria but only a slight increase in oleaginous yeasts.
- It is concluded that in fully functional yeast mitochondria, citrate efflux is limited by the amount of intra-mitochondrial citrate made available to the citrate translocator for exchange.
Labels:
Organism: Saccharomyces cerevisiae, Fungi
Enzyme: Inner mt-membrane transporter
Regulation: Ion;substrate transport, Substrate
Citrate, Malate, Pyruvate