Phosphoenolpyruvate metabolism in Jerusalem artichoke mitochondria |
| |
Authors: | Lidia de Bari Daniela Valenti Roberto Pizzuto Salvatore Passarella |
| |
Institution: | a Istituto di Biomembrane e Bioenergetica, CNR, Via G. Amendola 165/A, 70126, Bari, Italy b Dipartimento di Scienze della Salute, Università del Molise, Via De Sanctis, 86100, Campobasso, Italy |
| |
Abstract: | We report here initial studies on phosphoenolpyruvate metabolism in coupled mitochondria isolated from Jerusalem artichoke tubers. It was found that:- (1)
- phosphoenolpyruvate can be metabolized by Jerusalem artichoke mitochondria by virtue of the presence of the mitochondrial pyruvate kinase, shown both immunologically and functionally, located in the inner mitochondrial compartments and distinct from the cytosolic pyruvate kinase as shown by the different pH and inhibition profiles.
- (2)
- Jerusalem artichoke mitochondria can take up externally added phosphoenolpyruvate in a proton compensated manner, in a carrier-mediated process which was investigated by measuring fluorimetrically the oxidation of intramitochondrial pyridine nucleotide which occurs as a result of phosphoenolpyruvate uptake and alternative oxidase activation.
- (3)
- The addition of phosphoenolpyruvate causes pyruvate and ATP production, as monitored via HPLC, with their efflux into the extramitochondrial phase investigated fluorimetrically. Such an efflux occurs via the putative phosphoenolpyruvate/pyruvate and phosphoenolpyruvate/ATP antiporters, which differ from each other and from the pyruvate and the adenine nucleotide carriers, in the light of the different sensitivity to non-penetrant compounds. These carriers were shown to regulate the rate of efflux of both pyruvate and ATP. The appearance of citrate and oxaloacetate outside mitochondria was also found as a result of phosphoenolpyruvate addition.
|
| |
Keywords: | ADK adenylate kinase AOX alternative oxidase ALA alanine Ap5A P1 P5-di(adenosine-5&prime )pentaphosphate ARS arsenite ATP D S ATP detecting system BEMA benzylmalonate BF bathophenthroline BSA bovine serum albumin BTA benzentricarboxylic acid BUMA butylmalonate CF cytosolic fraction CAT carboxyatractyloside CN&minus potassium cyanide COX cytochrome oxidase α-CCN&minus α-cyano-4-hydroxycinnamate DPI diphenyleneiodonium chloride G6PDH glucose-6-phosphate dehydrogenase FCCP carbonyl cyanide 4-trifluoromethoxyphenylhydrazone G6PDH glucose-6-phosphate dehydrogenase HK hexokinase JAM Jerusalem artichoke mitochondria L-LDH L-lactate dehydrogenase ME malic enzyme OLIGO oligomycin OXA oxalate OAA oxaloacetate P D S pyruvate detecting system PEP phosphoenolpyruvate PEPC phosphoenolpyruvate carboxylase PhePYR phenylpyruvate Propyl-GALL propyl gallate PK pyruvate kinase ROT rotenone SD standard deviation SHAM salicylhydroxamic acid TX-100 Triton X-100 TX-JAM JAM solubilized with TX-100 |
本文献已被 ScienceDirect 等数据库收录! |
|