Acetyl-coenzyme A deacylase activity in liver is not an artifact. Subcellular distribution and substrate specificity of acetyl-coenzyme A deacylase activities in rat liver

Grigat, Klaus-P.; Koppe, Klaus; Seufert, Claus-D.; Söling, H.D.

doi:10.1042/bj1770071

Cited by 24 publications

(10 citation statements)

References 26 publications

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“…Furthermore, the activity of acetyl-CoA hydrolase of rat liver mitochondria is higher than the values we had reported previously [13]. The reason for this difference resides in the fact that in the present study we have corrected the values for the loss of mitochondrial enzyme occurring during isolation and purification of mitochondria by relating the values obtained with isolated sonicated mitochondria to the total hepatic glutamate dehydrogenase activity determined in the (Triton X-100)-treated total homogenate.…”

Section: Discussioncontrasting

confidence: 46%

“…It is not possible to quantify any possible product inhibition by free CoASH by using the Nbs2-coupled assay system. We therefore used an assay system in which the formation of ['4C]acetate from ['4C]acetyl-CoA is measured [13]. The initial content of free CoASH in the acetylCoA preparations used was from 1 -1 .I YO of acetyl-CoA.…”

Section: Control Of Acetyl-coa Hydrolase Activity By Coashmentioning

confidence: 99%

“…The difference between the two measurements was taken as the activity of acetyl-CoA hydrolase. The second assay system was performed as described previously using [l-'4C]acetyl-CoA as substrate [13].…”

Section: Determination Ojucetyl-coa Hydrolase Activitymentioning

confidence: 99%

“…Enzyme activities catalyzing acetyl-CoA hydrolysis have been found in various mammalian organs, in tumour tissue, and even in the blood . In liver, acetylCoA hydrolase was thought to be confined mainly to the mitochondrial compartment where we could locate it in the matrix space [13]. However, in 1980 Prass et al [I41 reported the additional existence in liver tissue of a cytosolic acetylCoA hydrolase which had been overlooked because of its extreme cold lability.…”

mentioning

confidence: 99%

“…Chem. 255, 521 5 -52231 has questioned the importance of mitochondrial acetyl-CoA hydrolase for the formation of free acetate [Grigat et al (1979) Biochem. J .…”

mentioning

confidence: 99%

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On the regulation of cold‐labile cytosolic and of mitochondrial acetyl‐CoA hydrolase in rat liver

Söling

Rescher

1985

European Journal of Biochemistry

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The discovery of a cold-labile cytosolic acetyl-CoA hydrolase of high activity in rat liver by Prass et al. [( 1980) J. Bid. Chem. 255, 521 5 -52231 has questioned the importance of mitochondrial acetyl-CoA hydrolase for the formation of free acetate [Grigat et al. (1979) Biochem. J . 177, 71 -791 under physiological conditions. Therefore this problem has been reevaluated by comparing various properties of the two enzymes.Cold-labile cytosolic acetyl-CoA hydrolase bands with an apparent MI of 68 000 during SDS/polyacrylamide gel electrophoresis, while the native enzyme elutes in two peaks with apparent MI of I36000 and 245000 during gel chromatography in the presence of 2 mM ATP. The mitochondrial enzyme elutes under the same conditions with an apparent M , of 157000. Under conditions where the cold-labile enzyme binds strongly to DEAE-BioGel and ATP-agarose, the mitochondrial enzyme remains unbound.The cold-labile enzyme can be activated 14-fold by ATP, half-maximal activation occurring already at 40 pM ATP. AdoPP[NH]P, AdoPP[CH2]P and GTP have a similar though weaker effect. ADP as well as GDP can completely inhibit the cold-labile enzyme with 50% inhibition occurring for both nucleotides at about 1.45 pM. The binding of ATP and ADP is competitive. Acetyl phosphate and pyrophosphate have no effect on the activity of the cold-labile enzyme. The mitochondrial acetyl-CoA hydrolase is not affected by these nucleotides. CoASH is a strong product inhibitor (z 80% inhibition at 40 pM CoASH) of the cold-labile enzyme, but only a weak inhibitor of the mitochondrial enzyme.Under in vivo conditions the activity of the cold-labile cytosolic acetyl-CoA hydrolase can be no more than 7% of the activity calculated for mitochondrial acetyl-CoA hydrolase under the same conditions. Accordingly the mitochondrial enzyme seems to be mainly responsible for the formation of free acetate by the intact liver, especially in view of the fact that the substrate specificity of the mitochondrial enzyme is much higher (activity ratios acetyl-CoA/butyryl-CoA 4.99 and 1 .I6 for the mitochondrial and the cold-labile enzyme respectively). Alloxan diabetes neither increased the activity of the cold-labile enzyme nor that of the mitochondrial enzyme. No experimental support has been found yet for the hypothesis that the acetyl-CoA hydrolase activity of the cold-labile enzyme represents the side-activity of an acetyl-transferase.

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Section: Discussioncontrasting

confidence: 46%

Section: Control Of Acetyl-coa Hydrolase Activity By Coashmentioning

confidence: 99%

Section: Determination Ojucetyl-coa Hydrolase Activitymentioning

confidence: 99%

mentioning

confidence: 99%

“…Chem. 255, 521 5 -52231 has questioned the importance of mitochondrial acetyl-CoA hydrolase for the formation of free acetate [Grigat et al (1979) Biochem. J .…”

mentioning

confidence: 99%

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