Acetyl-CoA C-acetyltransferase

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acetyl-CoA C-acetyltransferase
2WKT.png
Crystallographic structure of the tetrameric acetoacetyl-CoA thiolase (EC:2.3.1.9) from the Gram-negative bacterium Z. ramigera. [1]
Identifiers
EC no. 2.3.1.9
CAS no. 9027-46-7
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BRENDA BRENDA entry
ExPASy NiceZyme view
KEGG KEGG entry
MetaCyc metabolic pathway
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Gene Ontology AmiGO / QuickGO
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In enzymology, an acetyl-CoA C-acetyltransferase (EC 2.3.1.9) is an enzyme that catalyzes the chemical reaction

Contents

2 acetyl-CoA CoA + acetoacetyl-CoA

Hence, this enzyme has one substrate, acetyl-CoA, and two products, CoA and acetoacetyl-CoA.

Acetyl-CoA C-acetyltransferase belongs to the thiolase family of enzymes.

This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acetyl-CoA:acetyl-CoA C-acetyltransferase. Other names in common use include acetoacetyl-CoA thiolase, beta-acetoacetyl coenzyme A thiolase, 2-methylacetoacetyl-CoA thiolase [misleading], 3-oxothiolase, acetyl coenzyme A thiolase, acetyl-CoA acetyltransferase, acetyl-CoA:N-acetyltransferase, and thiolase II. This enzyme participates in 10 metabolic pathways: fatty acid metabolism, synthesis and degradation of ketone bodies, valine, leucine and isoleucine degradation, lysine degradation, tryptophan metabolism, pyruvate metabolism, benzoate degradation via coa ligation, propanoate metabolism, butanoate metabolism, and two-component system - general.

Isozymes

Human genes encoding acetyl-CoA C-acetyltransferases include:

acetyl-Coenzyme A acetyltransferase 1 (acetoacetyl Coenzyme A Thiolase)
Identifiers
Symbol ACAT1
NCBI gene 38
HGNC 93
OMIM 607809
RefSeq NM_000019
UniProt P24752
Other data
EC number 2.3.1.9
Locus Chr. 11 q22.3-23.1
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Structures Swiss-model
Domains InterPro
acetyl-Coenzyme A acetyltransferase 2 (acetoacetyl Coenzyme A thiolase)
Identifiers
Symbol ACAT2
NCBI gene 39
HGNC 94
OMIM 100678
RefSeq NM_005891
UniProt Q9BWD1
Other data
EC number 2.3.1.9
Locus Chr. 6 q25.3-q26
Search for
Structures Swiss-model
Domains InterPro

Related Research Articles

<span class="mw-page-title-main">Coenzyme A</span> Coenzyme, notable for its synthesis and oxidation role

Coenzyme A (CoA, SHCoA, CoASH) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle. All genomes sequenced to date encode enzymes that use coenzyme A as a substrate, and around 4% of cellular enzymes use it (or a thioester) as a substrate. In humans, CoA biosynthesis requires cysteine, pantothenate (vitamin B5), and adenosine triphosphate (ATP).

<span class="mw-page-title-main">Ketosis</span> Using body fats as fuel instead of carbohydrates

Ketosis is a metabolic state characterized by elevated levels of ketone bodies in the blood or urine. Physiological ketosis is a normal response to low glucose availability, such as low-carbohydrate diets or fasting, that provides an additional energy source for the brain in the form of ketones. In physiological ketosis, ketones in the blood are elevated above baseline levels, but the body's acid–base homeostasis is maintained. This contrasts with ketoacidosis, an uncontrolled production of ketones that occurs in pathologic states and causes a metabolic acidosis, which is a medical emergency. Ketoacidosis is most commonly the result of complete insulin deficiency in type 1 diabetes or late-stage type 2 diabetes. Ketone levels can be measured in blood, urine or breath and are generally between 0.5 and 3.0 millimolar (mM) in physiological ketosis, while ketoacidosis may cause blood concentrations greater than 10 mM.

<span class="mw-page-title-main">Acetyl-CoA</span> Chemical compound

Acetyl-CoA is a molecule that participates in many biochemical reactions in protein, carbohydrate and lipid metabolism. Its main function is to deliver the acetyl group to the citric acid cycle to be oxidized for energy production. Coenzyme A consists of a β-mercaptoethylamine group linked to the vitamin pantothenic acid (B5) through an amide linkage and 3'-phosphorylated ADP. The acetyl group of acetyl-CoA is linked to the sulfhydryl substituent of the β-mercaptoethylamine group. This thioester linkage is a "high energy" bond, which is particularly reactive. Hydrolysis of the thioester bond is exergonic (−31.5 kJ/mol).

<span class="mw-page-title-main">Ketogenesis</span> Chemical breakdown of ketone bodies

Ketogenesis is the biochemical process through which organisms produce ketone bodies by breaking down fatty acids and ketogenic amino acids. The process supplies energy to certain organs, particularly the brain, heart and skeletal muscle, under specific scenarios including fasting, caloric restriction, sleep, or others.

<span class="mw-page-title-main">Beta oxidation</span> Process of fatty acid breakdown

In biochemistry and metabolism, beta oxidation (also β-oxidation) is the catabolic process by which fatty acid molecules are broken down in the cytosol in prokaryotes and in the mitochondria in eukaryotes to generate acetyl-CoA, which enters the citric acid cycle, and NADH and FADH2, which are co-enzymes used in the electron transport chain. It is named as such because the beta carbon of the fatty acid undergoes oxidation to a carbonyl group. Beta-oxidation is primarily facilitated by the mitochondrial trifunctional protein, an enzyme complex associated with the inner mitochondrial membrane, although very long chain fatty acids are oxidized in peroxisomes.

Lipid metabolism is the synthesis and degradation of lipids in cells, involving the breakdown and storage of fats for energy and the synthesis of structural and functional lipids, such as those involved in the construction of cell membranes. In animals, these fats are obtained from food and are synthesized by the liver. Lipogenesis is the process of synthesizing these fats. The majority of lipids found in the human body from ingesting food are triglycerides and cholesterol. Other types of lipids found in the body are fatty acids and membrane lipids. Lipid metabolism is often considered as the digestion and absorption process of dietary fat; however, there are two sources of fats that organisms can use to obtain energy: from consumed dietary fats and from stored fat. Vertebrates use both sources of fat to produce energy for organs such as the heart to function. Since lipids are hydrophobic molecules, they need to be solubilized before their metabolism can begin. Lipid metabolism often begins with hydrolysis, which occurs with the help of various enzymes in the digestive system. Lipid metabolism also occurs in plants, though the processes differ in some ways when compared to animals. The second step after the hydrolysis is the absorption of the fatty acids into the epithelial cells of the intestinal wall. In the epithelial cells, fatty acids are packaged and transported to the rest of the body.

<span class="mw-page-title-main">HMG-CoA</span> Chemical compound

β-Hydroxy β-methylglutaryl-CoA (HMG-CoA), also known as 3-hydroxy-3-methylglutaryl coenzyme A, is an intermediate in the mevalonate and ketogenesis pathways. It is formed from acetyl CoA and acetoacetyl CoA by HMG-CoA synthase. The research of Minor J. Coon and Bimal Kumar Bachhawat in the 1950s at University of Illinois led to its discovery.

<span class="mw-page-title-main">Acyl-CoA</span>

Acyl-CoA is a group of coenzymes that metabolize fatty acids. Acyl-CoA's are susceptible to beta oxidation, forming, ultimately, acetyl-CoA. The acetyl-CoA enters the citric acid cycle, eventually forming several equivalents of ATP. In this way, fats are converted to ATP, the universal biochemical energy carrier.

<span class="mw-page-title-main">Acetoacetyl-CoA</span> Chemical compound

Acetoacetyl CoA is the precursor of HMG-CoA in the mevalonate pathway, which is essential for cholesterol biosynthesis. It also takes a similar role in the ketone bodies synthesis (ketogenesis) pathway of the liver. In the ketone bodies digestion pathway, it is no longer associated with having HMG-CoA as a product or as a reactant.

<span class="mw-page-title-main">Thiolase</span> Enzymes

Thiolases, also known as acetyl-coenzyme A acetyltransferases (ACAT), are enzymes which convert two units of acetyl-CoA to acetoacetyl CoA in the mevalonate pathway.

<span class="mw-page-title-main">ACAT1</span> Protein-coding gene in the species Homo sapiens

Acetyl-CoA acetyltransferase, mitochondrial, also known as acetoacetyl-CoA thiolase, is an enzyme that in humans is encoded by the ACAT1 gene.

<span class="mw-page-title-main">3-hydroxyacyl-CoA dehydrogenase</span> Enzyme

In enzymology, a 3-hydroxyacyl-CoA dehydrogenase (EC 1.1.1.35) is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Isovaleryl-CoA dehydrogenase</span>

In enzymology, an isovaleryl-CoA dehydrogenase is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">3-oxoacid CoA-transferase</span> Enzyme family

In enzymology, a 3-oxoacid CoA-transferase is an enzyme that catalyzes the chemical reaction

In enzymology, an acetate CoA-transferase is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Carnitine O-octanoyltransferase</span>

Carnitine O-octanoyltransferase is a member of the transferase family, more specifically a carnitine acyltransferase, a type of enzyme which catalyzes the transfer of acyl groups from acyl-CoAs to carnitine, generating CoA and an acyl-carnitine. The systematic name of this enzyme is octanoyl-CoA:L-carnitine O-octanoyltransferase. Other names in common use include medium-chain/long-chain carnitine acyltransferase, carnitine medium-chain acyltransferase, easily solubilized mitochondrial carnitine palmitoyltransferase, and overt mitochondrial carnitine palmitoyltransferase. Specifically, CROT catalyzes the chemical reaction:

<span class="mw-page-title-main">Homocitrate synthase</span> Enzyme

In enzymology, a homocitrate synthase (EC 2.3.3.14) is an enzyme that catalyzes the chemical reaction

<span class="mw-page-title-main">Hydroxymethylglutaryl-CoA synthase</span> Class of enzymes

In molecular biology, hydroxymethylglutaryl-CoA synthase or HMG-CoA synthase EC 2.3.3.10 is an enzyme which catalyzes the reaction in which acetyl-CoA condenses with acetoacetyl-CoA to form 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA). This reaction comprises the second step in the mevalonate-dependent isoprenoid biosynthesis pathway. HMG-CoA is an intermediate in both cholesterol synthesis and ketogenesis. This reaction is overactivated in patients with diabetes mellitus type 1 if left untreated, due to prolonged insulin deficiency and the exhaustion of substrates for gluconeogenesis and the TCA cycle, notably oxaloacetate. This results in shunting of excess acetyl-CoA into the ketone synthesis pathway via HMG-CoA, leading to the development of diabetic ketoacidosis.

<span class="mw-page-title-main">OXCT1</span> Protein-coding gene in the species Homo sapiens

3-oxoacid CoA-transferase 1 (OXCT1) is an enzyme that in humans is encoded by the OXCT1 gene. It is also known as succinyl-CoA-3-oxaloacid CoA transferase (SCOT). Mutations in the OXCT1 gene are associated with succinyl-CoA:3-oxoacid CoA transferase deficiency. This gene encodes a member of the 3-oxoacid CoA-transferase gene family. The encoded protein is a homodimeric mitochondrial matrix enzyme that plays a central role in extrahepatic ketone body catabolism by catalyzing the reversible transfer of coenzyme A (CoA) from succinyl-CoA to acetoacetate.

Acetoacetyl-CoA synthase (EC 2.3.1.194, NphT7) is an enzyme with systematic name acetyl-CoA:malonyl-CoA C-acetyltransferase (decarboxylating). This enzyme catalyses the following chemical reaction

References

  1. PDB: 2WKT ; Meriläinen G, Poikela V, Kursula P, Wierenga RK (November 2009). "The thiolase reaction mechanism: the importance of Asn316 and His348 for stabilizing the enolate intermediate of the Claisen condensation". Biochemistry. 48 (46): 11011–25. doi:10.1021/bi901069h. PMID   19842716.

Further reading