Decarboxylation of malonyl-CoA by lactating bovine mammary fatty acid synthase

Svoronos, Soraya; Kumar, Soma

doi:10.1016/0305-0491(88)90058-2

Cited by 2 publications

(1 citation statement)

References 23 publications

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“…Lactate dehydrogenase (EC 1.1.1.27) was assayed spectrophotometrically at 25 mC [25]. MDC (EC 4.1.1.9) was assayed spectrophotometrically in a 1 ml reaction volume at 37 mC in a split-beam spectrophotometer, using a minor modification of the method of Svoronos and Kumar [26], which itself was a modification of the original method described in [27]. The reaction mixture initially contained 0.1 M Tris\HCl (pH 8.0), 0.1 M sucrose, 0.5 mM dithiothreitol, 5 µM rotenone, 10 mM -malate, 0.5 mM NAD + and 8.5 units of malate dehydrogenase.…”

Section: Enzyme Assaysmentioning

confidence: 99%

Malonyl-CoA metabolism in cardiac myocytes

HAMILTON

Saggerson

2000

Biochem. J.

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(1) Malonyl-CoA is thought to play a signalling role in fuel-selection in cardiac muscle, but the rate at which the concentration of this potential signal can be changed has not previously been investigated. (2) Rapid changes in cellular malonyl-CoA could be observed when rat cardiac myocytes were incubated in glucose-free medium followed by re-addition of 5 mM glucose, or when cells were transferred from a medium containing glucose to a glucose-free medium. On addition of glucose, malonyl-CoA increased by 62% to a new steady-state level, at a rate of at least 0.4 nmol/g dry wt. per min. The half-time of this change was less than 3 min. After removal of glucose the malonyl-CoA content was estimated to decline by 0.43-0.55 nmol/g dry wt. per min. (3) Malonyl-CoA decarboxylase (MDC) is a possible route for disposal of malonyl-CoA. No evidence was obtained for a cytosolic activity of MDC in rat heart where most of the activity was found in the mitochondrial fraction. MDC in the mitochondrial matrix was not accessible to extramitochondrial malonyl-CoA. However, approx. 16% of the MDC activity in mitochondria was overt, in a manner that could not be explained by mitochondrial leakage. It is suggested that this, as yet uncharacterized, overt MDC activity could provide a route for disposal of cytosolic malonyl-CoA in the heart. (4) No activity of the condensing enzyme for the fatty acid elongation system could be detected in any heart subcellular fraction using two assay systems. A previous suggestion [Awan and Saggerson (1993) Biochem. J. 295, 61-66] that this could provide a route for disposal of cytosolic malonyl-CoA in heart should therefore be abandoned.

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Section: Enzyme Assaysmentioning

confidence: 99%