Acyl-CoA

About: Acyl-CoA is a research topic. Over the lifetime, 527 publications have been published within this topic receiving 25134 citations. The topic is also known as: Acyl Coenzyme A.

Carnitine metabolism in livers and hearts of 48h-starved rats: the contribution of fat and carbohydrate to acylcarnitine formation.

Abstract: The work investigated the effects of administration of 2-tetradecylglycidate (TDG), an inhibitor of mitochondrial long-chain fatty acid oxidation, alone or in combination with glucose, on concentrations of free and acylated carnitine in livers and hearts of 48 h-starved rats. The only significant effect of TDG in the heart was to decrease [short-chain acylcarnitine]. This demonstrates that in heart, fat oxidation is linked to the formation of short-chain acylcarnitine. Cardiac [short-chain acylcarnitine] was not significantly decreased by TDG if the rats were also administered glucose, suggesting that acyl CoA derived from glucose may be used for short-chain acylcarnitine formation in TDG-treated rats. TDG significantly decreased in [free carnitine]. No changes in [short-chain acylcarnitine] were observed. This indicates that formation of short-chain acylcarnitine in liver is not determined by the rates of fat oxidation. It was calculated that at least 63% of the acyl-groups esterified to carnitine were generated by intramitochondrial beta-oxidation. The effects of glucose and TDG on hepatic concentrations of free and long-chain acylcarnitine were additive, suggesting that extramitochondrial fat oxidation can contribute to acylcarnitine formation in liver.

Comparison of metabolic fluxes of cis-5-enoyl-CoA and saturated acyl-CoA through the beta-oxidation pathway.

Abstract: The metabolic fluxes of cis-5-enoyl-CoAs through the beta-oxidation cycle were studied in solubilized rat liver mitochondrial samples and compared with saturated acyl-CoAs of equal chain length. These studies were accomplished using either spectrophotometric assay of enzyme activities and/or the analysis of metabolites and precursors using a gas chromatographic method after conversion of CoA esters into their free acids. Cis-5-enoyl-CoAs were dehydrogenated by acyl-CoA oxidase or acyl-CoA dehydrogenases at significantly lower rates (10-44%) than saturated acyl-CoAs. However, enoyl-CoA hydratase hydrated trans-2-cis-5-enoyl-CoA at a faster rate (at least 1.5-fold) than trans-2-enoyl-CoA. The combined activities of 3-hydroxyacyl-CoA dehydrogenase and 3-ketoacyl-CoA thiolase for 3-hydroxy-cis-5-enoyl-CoAs derived from cis-5-enoyl-CoAs were less than 40% of the activity for the corresponding 3-hydroxyacyl-CoAs prepared from saturated acyl-CoAs. Rat liver mitochondrial beta-oxidation enzymes were capable of metabolizing cis-5-enoyl-CoA via one cycle of beta-oxidation to cis-3-enoyl-CoA with two less carbons. However, the overall rates of one cycle of beta-oxidation, as determined with stable-isotope-labelled tracer, was only 15-25%, for cis-5-enoyl-CoA, of that for saturated acyl-CoA. In the presence of NADPH, the metabolism of cis-5-enoyl-CoAs was switched to the reduction pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

VII. Decrease in the Rate of Respiration in the Spermatozoa of the Sea Urchin, Hemicentrotus Pulcherrimus, Caused by Long Chain Fatty Acyl-CoA-induced Inhibition of the Movement. (sperm movement/carnitine/palmitoyl-CoA/sperm-egg interaction/sperm respiration)

Abstract: Spermatozoa of the sea urchin, Hemicentrotus pulcherrimus, showed marked decrease in respiration, and arrested movement after interaction with the fixed eggs. Immotile spermatozoa that had reacted with fixed eggs contained higher levels of long chain fatty acyl-CoAs than normal motile spermatozoa. On treatment with carnitine, the immotile spermatozoa became motile again and their intracellular concentrations of long chain fatty acyl-CoAs decreased. On incubation with anti-mycin A or CN− for 20 min, the motility of normal spermatozoa decreased gradually but their long chain fatty acyl-CoA content changed only slightly. The decrease in sperm motility in the latter case was probably due to decrease in the level of ATP, resulting from inhibition of respiration by antimycin A or CN−. The motility of spermatozoa extracted with Triton X-100 was restored by ATP and their movement was inhibited by long chain fatty acyl-CoAs, such as myristoly CoA and palmitoyl-CoA, but was not by short chain fatty acyl-CoAs, such as acetyl-CoA, propionyl CoA and butyryl-CoA. Na-palmitate, Na-myristate and CoA did not inhibit the reactivation of extracted spermatozoa by ATP.

REGULATION OF ADENINE NUCLEOTIDE TRANSLOCATION BY LONG CHAIN FATTY ACYL CoA ESTERS

Abstract: Publisher Summary This chapter discusses the regulation of adenine nucleotide translocation by long chain fatty acyl CoA esters. The adenine nucleotide translocase is recognized to be one of the most important enzymes in cell bioenergetics. A model for the mechanism of adenine nucleotide translocation had to take into consideration the asymmetry of the binding of the inhibitors. Long chain fatty acyl CoA esters are the natural effectors of the adenine nucleotide translocator. The receptors on the ADP/ATP carrier for the acyl CoA esters are asymmetric or in different conformational states in that when the acyl CoA is bound to the cytosolic side of the inner membrane, it inhibits like atractylate, whereas when it is bound to the matrix side of the inner membrane, the acyl CoA inhibits like bongkrekic acid. Long chain acyl CoA esters can be physiologically translocated across the inner mitochondrial membrane by the acylcarnitine transferase enzymes and the carnitine-acylcarnitine translocase system.