Pyruvate dehydrogenase complex from ribbed mussel gill mitochondria

✍ Scribed by Paynter, Kennedy T. ;Karam, George A. ;Ellis, Lehman L. ;Bishop, Stephen H.

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 604 KB
• Volume: 236
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402360302

✦ Synopsis

The pyruvate dehydrogenase complex has been demonstrated in high speed pellet preparations from sonicated ribbed mussel gill mitochondria. The activity of the complex is inhibited by low chloride (< 100 mM) concentrations, EDTA (1 mM), succinate, ATP, and NAD/NADH ratios below 4. Inhibition by EDTA is relieved by addition of 10 mM MgC12-1 mM CaC12.

ATP inhibition was enhanced by NaF and reversed by high Mg++ concentrations in the absence of NaF. Pyruvate and thiamine pyrophosphate inhibited the inactivation by ATP. The nonhydrolyzable ATP analog AMP-PNP caused inhibition of the overall catalytic activity that was identical to ATP. Factors involved in the ATP inhibition and Mg++ reversal are lost with freezing or cold storage. Preliminary results using y3'P-ATP indicate that a protein kinase that phosphorylates the a! subunit of E l (pyruvate dehydrogenase) from the mammalian PDC is associated with the gill PDC. The activity of the complex may be regulated by a phosphorylatioddephosphorylation mechanism and by the relative levels of substrates, products, and other metabolites in the mitochondria.