Acetate-CoA ligase

This enzyme [EC 6.2.1.1], also referred to as acetate-CoA ligase or acetate thiokinase, catalyzes the reaction of acetate, coenzyme A, and ATP to form acetyl-CoA, AMP, and pyrophosphate. The enzyme will also utilize propanoate and propenoate as substrates. 

Many enzymes have a specific requirement for potassium. In certain instances, potassium may act along with certain other ions in influencing enzyme activity besides ATPase examples include L-serine hydrolase, L-threonine hydrolase, S-adenosylme-thionine, L-tyrosine-RNA ligase, propionyl-CoA C02 ligase, and acetate CoA ligase (Oberleas etal. 1999). 

EC6. Ligases enzymes that catalyze the joining of two molecules with concomitant hydrolysis of the diphosphate bond in ATP or a similar triphosphate. Ligase is commonly used for the common name, but, in a few cases, synthase or carboxylase is used. Example acetate CoA ligase (EC 6.2.1.1)... 

We now explore the remarkable process by which a long-chain saturated fatty acid is converted into two-carbon units (acetate), which can be oxidized to C02 and H20 via the tricarboxylic acid cycle and the electron-transport chain. Fatty acids that enter cells are activated to their CoA derivatives by the enzyme acyl-CoA ligase and transported into the mitochondria for /3 oxidation as we discuss later in this chapter. 

Figure 1. Proposed biosynthetic pathway to monolignols, and related metabolites, a. Phenylalanine ammonia-lyase, b. Tyrosine ammonia-lyase, c. Cinnamate-4-hydroxylase, d. p-Coumarate-3-hydroxylase, e. O-Methyltransferase, f. Ferulate-5-hydroxylase, g. Hydroxycinnamate-CoA ligase, h. Cinnamoyl-CoA NADP oxidoreductase, i. Cinnamyl alcohol dehydrogenase. ( Note plus acetate pathway for both flavonoids and suberin)...

ACETATE KINASE ACETYL-CoA CARBOXYLASE ACETYL-CoA SYNTHETASE N-ACETYLCLUCOSAMINE KINASE ACTIN ATPase ACTOMYOSIN ATPase N-ACYLMANNOSAMINE KINASE ADENINE NUCLEOTIDE TRANSLOCASE ADENOSINE KINASE ADENYLATE KINASE (MYOKINASE) ADENYLYLSULFATE KINASE d-ALANINE-d-ALANINE LIGASE... 

Acetyl-CoA is formed from CoA and acetate by the enzyme acetyl-CoA synthetase, an ADP-forming ligase. Phosphotrans-acetylase forms acetyl-CoA from CoA and acetyl-phosphate, which in turn is formed from acetate and ATP catalyzed by acetate kinase. Other enzymes that can form acetyl-CoA from CoA and other acetyl group donors include ATP citrate lyase and thiolase. Longer chain acyl-CoA thioesters are typically formed from CoA and a fatty acid catalyzed by ligases generally known as acyl-CoA synthetases. 

The ligases, as the name implies, catalyse reactions where two molecules are bound together, with the breakdown of high-energy phosphate bonds such as in ATP, which provides the energy for the reaction to take place. The production of acetyl-CoA from acetate by acetyl coenzyme A synthetase is typical ... 

Within bacteria, citric acid is split into an oxaloacetate molecule and an acetate molecule by the lyase (Figure 5.6). The largest quantities of this enzyme are synthesized in low sugar concentration media containing citric acid. Glucose acts as a repressor. The protein is active in an acetylated form. The inactive deacetylated form can be reacetylated in vivo by the citrate lyase ligase with acetyl CoA or acetate and ATP. This... 

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