What is Acetyl CoA 3. What is Acyl CoA 4. Acetyl CoA or acetyl Coenzyme A is an important molecule involved in the metabolism of proteins, carbohydrates, and lipids. It is useful in delivering the acetyl functional group to the Krebs cycle for the production of energy. Acetyl CoA forms from the combination of several amino acids, pyruvate, and fatty acids. Acetylating the CoA gives acetyl CoA, and this occurs via the glycolysis of carbohydrates and beta-oxidation of fatty acids.
This molecule has a thioester linkage which is highly reactive due to its high energy content. Therefore, the hydrolysis of this thioester bond is exergonic which means, it releases energy to the surrounding. Acyl CoA is an important molecule used in fatty acid metabolism. It is a group of coenzymes. This compound has a coenzyme A attached to a fatty acid chain. Metabolic engineering strategies were then applied in the E.
The recombinant strains , Ack, and were used to compare acetyl-CoA supplied from 80 mM glucose, mM acetate, and 20 mM palmitic acid for NAG production, respectively. The molar weights of glucose, acetate, and palmitic acid used theoretically produced mM acetyl-CoA. For NAG synthesis, glucose was the most efficient carbon source, but acetate and fatty acid also showed good performance. The results demonstrated the great potential of acetate and fatty acid for supplying acetyl-CoA.
The strategies developed in this study may be potentially applicable for producing not only acetyl-CoA-derived metabolites, but also a wide range of useful compounds that require acetylation in the pathway.
However, further engineering is required to enhance the utilization of acetate and fatty acid by E. The bacteria strains and plasmids used in this study are listed in Table 3. The plasmids pRB1 s and pSB1a used for gene expression were derived from expression vectors previously developed in our laboratory unpublished and have the following features: a promoter araBAD , multiple cloning sites, rrnB terminator, origin of replication RSF and pSC, and streptomycin and ampicillin resistance genes.
The templates for NAG synthase genes from T. The plasmids pAcs and pAck were constructed by introducing the acs and ackA-pta operons of E. For chromosomal phenotype integration, P1 virus-mediated transfection was performed as described by Thomason et al. The primers used in this study are listed in Additional file 1 : Table S1. Luria-Bertani LB medium per liter: tryptone 10 g, yeast extract 5 g, NaCl 10 g was used for all molecular construction experiments and strain cultures.
Whole-cell biocatalysis was used for NAG production [ 36 ]. Cells induced overnight were harvested by centrifugation at rpm for 10 min and washed with 0. The substrate glucose, acetate, or fatty acid was supplemented frequently in small amounts based on the experimental conditions.
The scale-up of bioconversion was carried out in a 1-L fermenter containing mL bioconversion medium. Cells were induced first in a 5-L fermenter containing 2 L auto-inducing ZYM medium similar to that in the shake flasks, and then the cells were harvested by centrifugation. The pH was maintained at 7. NAGS activity was assayed spectrophotometrically by measuring the increase in absorbance at nm due to the formation of 5-thionitrobenzoate resulting from the reaction between the sulfhydryl group of CoASH, generated by the amino acid acetylating activity, and 5,5-dithio-bis 2-nitrobenzoic acid DTNB as previously reported [ 37 ].
For substrate inhibition analysis, 5 groups of bioconversion media were used containing 50 mM glucose and different concentrations of glutamate 50, , , and mM and 1 M. The product inhibition experiment was carried out by adding different concentrations of NAG 0, 20, 40, 70 and mM to the conversion medium containing 50 mM glutamate and 50 mM glucose.
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Mol Syst Biol. Google Scholar. Enzymatic assembly of DNA molecules up to several hundred kilobases. Nat Methods. Curr Protoc Mol Biol. Studier FW. However, at low glucose levels, acetyl CoA in the cytosol forms ketone bodies released by the liver into the blood. These ketone bodies can even cross the blood-brain barrier to serve as fuel to the cells in the central nervous system. Therefore, high levels of ketone bodies in the blood indicate starvation, prolonged heavy exercises, low carbohydrate diet, ketosis or even ketoacidosis.
Acyl CoA is a group of coenzymes important in fatty acid metabolism. Therefore, acyl CoA is a key biochemical component in converting fat into energy. Acyl CoA basically forms in a two-step reaction known as fatty acid activation. Acyl CoA synthetase is the enzyme responsible for the above reaction.
Moreover, the three structural components of the acyl CoA are the R group, carbonyl group, and the coenzyme A. Here, the R group is variable and is essentially a side chain of fatty acids. However, the length of the R group depends on the type of acyl CoA synthetase enzyme that takes part in the reaction. Moreover, acyl CoA can have three fates depending on the type of enzyme. They are the formation of carbon acyl-CoA by the enzyme, medium-chain acyl-CoA synthase , the formation of Acyl-CoA by a different acyl-CoA synthetase enzyme, and the formation of free fatty acid and coenzyme A by the enzyme, a cyl-CoA thioesterase , which posses the opposite enzymatic activity to acyl CoA synthetase.
Cytosolic acyl CoA is transported into mitochondria by means of carnitine participants.
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