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Coenzyme A

 

 
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Coenzyme A
 
 
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Coenzyme A (CoA, CoASH, or HSCoA) is a coenzyme
Coenzyme

Many enzymes require a cofactor for catalytic activity, accelerating the transformation of a specific substrate to a particular product. The inactive protein, without the cofactor is called an apoenzyme, while the complete enzyme with cofactor is the holoenzyme....
, notable for its role in the synthesis
Fatty acid metabolism

Fatty acids are an important source of energy for many organisms. Excess glucose can be stored efficiently as fat. Triglycerides yield more than twice as much energy for the same mass as do carbohydrates or proteins....
 and oxidation
Fatty acid metabolism

Fatty acids are an important source of energy for many organisms. Excess glucose can be stored efficiently as fat. Triglycerides yield more than twice as much energy for the same mass as do carbohydrates or proteins....
 of fatty acid
Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturation or Unsaturated compound....
s, and the oxidation of pyruvate
Pyruvic acid

Pyruvic acid is an organic acid. It is also a ketone. It is the simplest keto acids. The carboxylate ion of pyruvic acid is known as pyruvate....
 in the citric acid cycle
Citric acid cycle

The citric acid cycle ? also known as the tricarboxylic acid cycle ; the Krebs cycle; or, more rarely, the Szent-Gy?rgyi-Krebs cycle) ? is a series of enzyme-catalysed chemical reactions of central importance in all living cell s that use oxygen as part of cellular respiration....
. It is adapted from cysteamine
Cysteamine

Cysteamine is the chemical compound with the formula HSCH2CH2NH2. It is the simplest stable aminothiol and a degradation product of the amino acid cysteine....
, pantothenate
Pantothenic acid

Pantothenic acid, also called vitamin B5 , is a water-soluble vitamin required to sustain life . Pantothenic acid is needed to form coenzyme-A , and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats....
, and adenosine triphosphate
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
.

zyme A is synthesized in a five-step process from pantothenate:
  1. Pantothenate (Vitamin B5) is phosphorylated to 4'-phosphopantothenate by the enzyme pantothenate kinase
    Pantothenate kinase

    Pantothenate kinase is the first enzyme in the biosynthetical pathway of Coenzyme A. It phophorylates pantothenate to form 4'-phosphopantothenate....
     (PanK; CoaA; CoaX)
  2. A cysteine is added to 4'-phosphopantothenate by the enzyme phosphopantothenoylcysteine synthetase
    Phosphopantothenoylcysteine synthetase

    Human phosphopantothenoylcysteine synthetase is a dimer with identical monomers.ReferencesStructure of human phosphopantothenoylcysteine synthetase at 2.3 A resolution....
     (PPC-DC; CoaB) to form 4'-phospho-N-pantothenoylcysteine (PPC)
  3. PPC is decarboxylated to 4'-phosphopantetheine
    Pantetheine

    Pantetheine is the cysteamine amide analog of pantothenic acid . The dimer of this compound, pantethine is more commonly known, and is considered to be a more potent form of vitamin B5 than pantothenic acid....
     by phosphopantothenoylcysteine decarboxylase
    Phosphopantothenoylcysteine decarboxylase

    In enzymology, a phosphopantothenoylcysteine decarboxylase is an enzyme that catalysis the chemical reactionHence, this enzyme has one substrate , N-[-4'-phosphopantothenoyl]-L-cysteine, and two product , pantotheine 4'-phosphate and carbon dioxide....
     (CoaC)
  4. 4'-phosphopantetheine
    Pantetheine

    Pantetheine is the cysteamine amide analog of pantothenic acid . The dimer of this compound, pantethine is more commonly known, and is considered to be a more potent form of vitamin B5 than pantothenic acid....
     is adenylylated to form dephospho-CoA by the enzyme phosphopantetheine adenylyl transferase (CoaD)
  5. Finally, dephospho-CoA is phosphorylated using ATP to coenzyme A by the enzyme dephosphocoenzyme A kinase (CoaE).


e coenzyme A is chemically a thiol
Thiol

In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group....
, it can react with carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s to form thioester
Thioester

Thioesters are compounds resulting from the bonding of sulfur with an acyl group with the general formula R-S-CO-R. They are the product of esterification between a carboxylic acid and a thiol ....
s, thus functioning as an acyl
Acyl

An acyl group is a functional group derived by the removal of one or more hydroxyl groups from an oxoacid.. In organic chemistry, the acyl group is usually derived from a carboxylic acid of the form RCarbon Oxygen hydroxyl....
 group carrier.






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Coenzyme A (CoA, CoASH, or HSCoA) is a coenzyme
Coenzyme

Many enzymes require a cofactor for catalytic activity, accelerating the transformation of a specific substrate to a particular product. The inactive protein, without the cofactor is called an apoenzyme, while the complete enzyme with cofactor is the holoenzyme....
, notable for its role in the synthesis
Fatty acid metabolism

Fatty acids are an important source of energy for many organisms. Excess glucose can be stored efficiently as fat. Triglycerides yield more than twice as much energy for the same mass as do carbohydrates or proteins....
 and oxidation
Fatty acid metabolism

Fatty acids are an important source of energy for many organisms. Excess glucose can be stored efficiently as fat. Triglycerides yield more than twice as much energy for the same mass as do carbohydrates or proteins....
 of fatty acid
Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturation or Unsaturated compound....
s, and the oxidation of pyruvate
Pyruvic acid

Pyruvic acid is an organic acid. It is also a ketone. It is the simplest keto acids. The carboxylate ion of pyruvic acid is known as pyruvate....
 in the citric acid cycle
Citric acid cycle

The citric acid cycle ? also known as the tricarboxylic acid cycle ; the Krebs cycle; or, more rarely, the Szent-Gy?rgyi-Krebs cycle) ? is a series of enzyme-catalysed chemical reactions of central importance in all living cell s that use oxygen as part of cellular respiration....
. It is adapted from cysteamine
Cysteamine

Cysteamine is the chemical compound with the formula HSCH2CH2NH2. It is the simplest stable aminothiol and a degradation product of the amino acid cysteine....
, pantothenate
Pantothenic acid

Pantothenic acid, also called vitamin B5 , is a water-soluble vitamin required to sustain life . Pantothenic acid is needed to form coenzyme-A , and is critical in the metabolism and synthesis of carbohydrates, proteins, and fats....
, and adenosine triphosphate
Adenosine triphosphate

This article is about the chemical used by cells as an energy carrier. For other uses, see ATP .Adenosine-5'-triphosphate is a multifunctional nucleotide, and plays an important role in cell biology as a coenzyme that is the "molecule unit of currency" of intracellular energy transfer....
.

Biosynthesis

Coenzyme A is synthesized in a five-step process from pantothenate:
  1. Pantothenate (Vitamin B5) is phosphorylated to 4'-phosphopantothenate by the enzyme pantothenate kinase
    Pantothenate kinase

    Pantothenate kinase is the first enzyme in the biosynthetical pathway of Coenzyme A. It phophorylates pantothenate to form 4'-phosphopantothenate....
     (PanK; CoaA; CoaX)
  2. A cysteine is added to 4'-phosphopantothenate by the enzyme phosphopantothenoylcysteine synthetase
    Phosphopantothenoylcysteine synthetase

    Human phosphopantothenoylcysteine synthetase is a dimer with identical monomers.ReferencesStructure of human phosphopantothenoylcysteine synthetase at 2.3 A resolution....
     (PPC-DC; CoaB) to form 4'-phospho-N-pantothenoylcysteine (PPC)
  3. PPC is decarboxylated to 4'-phosphopantetheine
    Pantetheine

    Pantetheine is the cysteamine amide analog of pantothenic acid . The dimer of this compound, pantethine is more commonly known, and is considered to be a more potent form of vitamin B5 than pantothenic acid....
     by phosphopantothenoylcysteine decarboxylase
    Phosphopantothenoylcysteine decarboxylase

    In enzymology, a phosphopantothenoylcysteine decarboxylase is an enzyme that catalysis the chemical reactionHence, this enzyme has one substrate , N-[-4'-phosphopantothenoyl]-L-cysteine, and two product , pantotheine 4'-phosphate and carbon dioxide....
     (CoaC)
  4. 4'-phosphopantetheine
    Pantetheine

    Pantetheine is the cysteamine amide analog of pantothenic acid . The dimer of this compound, pantethine is more commonly known, and is considered to be a more potent form of vitamin B5 than pantothenic acid....
     is adenylylated to form dephospho-CoA by the enzyme phosphopantetheine adenylyl transferase (CoaD)
  5. Finally, dephospho-CoA is phosphorylated using ATP to coenzyme A by the enzyme dephosphocoenzyme A kinase (CoaE).


Function

Since coenzyme A is chemically a thiol
Thiol

In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group....
, it can react with carboxylic acid
Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the Chemical formula -COH, usually written -COOH or -CO2H....
s to form thioester
Thioester

Thioesters are compounds resulting from the bonding of sulfur with an acyl group with the general formula R-S-CO-R. They are the product of esterification between a carboxylic acid and a thiol ....
s, thus functioning as an acyl
Acyl

An acyl group is a functional group derived by the removal of one or more hydroxyl groups from an oxoacid.. In organic chemistry, the acyl group is usually derived from a carboxylic acid of the form RCarbon Oxygen hydroxyl....
 group carrier. It assists in transferring fatty acid
Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturation or Unsaturated compound....
s from the cytoplasm
Cytoplasm

The cytoplasm is the part of a Cell that is enclosed within the plasma membrane. In eukaryote cells the cytoplasm contains organelles, such as mitochondrion, that are filled with liquid kept separate from the rest of the cytoplasm by biological membranes....
 to mitochondria. A molecule of coenzyme A carrying an acetyl
Acetyl

In organic chemistry, acetyl , is a functional group, the acyl of acetic acid, with chemical formula -CarbonOxygenCarbonHydrogen3. It is sometimes abbreviated as Ac ....
 group is also referred to as acetyl-CoA
Acetyl-CoA

Acetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidation for energy production....
. When it is not attached to an acyl group it is usually referred to as 'CoASH' or 'HSCoA'.

List of coenzyme A activated acyl groups

  • Acetyl-CoA
    Acetyl-CoA

    Acetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidation for energy production....
  • Propionyl-CoA
    Propionyl-CoA

    Propionyl-CoA is a coenzyme A derivative of propionic acid....
  • Acetoacetyl-CoA
  • Coumaroyl-CoA
    Coumaric acid

    Coumaric acids are organic compounds that are hydroxy derivatives of cinnamic acid. There are three isomers, o-coumaric acid, m-coumaric acid, and p-coumaric acid, that differ by the position of the hydroxy substitution of the phenyl group....
     (used in flavonoid
    Flavonoid

    The term flavonoid refers to a class of plant secondary metabolites. According to the IUPAC nomenclature, they can be classified into:*flavonoids, derived from 2-phenylchromone structure...
     and stilbenoid biosynthesis)
  • Acyl derived from dicarboxylic acid
    Dicarboxylic acid

    Dicarboxylic acids are organic compounds that are substituted with two carboxylic acid functional groups. In molecular formulae for dicarboxylic acids, these groups are often written as HOOC-R-COOH, where R is usually an alkane, alkene, or alkyne group....
    s
    • Malonyl-CoA
      Malonyl-CoA

      Malonyl-CoA is a coenzyme A derivative....
    • Succinyl-CoA
      Succinyl-CoA

      Succinyl-Coenzyme A, generally abbreviated as Succinyl-CoA or SucCoA is a combination of succinic acid and coenzyme A....
    • Hydroxymethylglutaryl-CoA (used in isoprenoid biosynthesis)
    • Pimelyl-CoA (used in biotin
      Biotin

      Biotin, also known as vitamin H or B7, has the chemical formula C10H16N2O3S , is a water-soluble B-complex vitamin which is composed of an ureido ring fused with a tetrahydrothiophene ring....
       biosynthesis)


  • Butyryl CoA


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