Metabolism fatty acid

Regulatory Control of Fatty Acid Metabolism—An Interplay of Allosteric Modifiers and Phosphorylation-Dephosphorylation Cycles... 

Acyl-CoAs are the activated intermediates of fatty acid metabolism formed by the condensation of fatty acids with Coenzyme A. 

Figure 9. Fatty acid metabolism in skeletal muscle.

Di Mauro, S., Bonilla, E., Hays, A.P., Ricci. E. (1992). Skeletal muscle storage diseases resulting from errors in carbohydrate and fatty acid metabolism. In Skeletal Muscle Pathology (Mastaglia, F.L., Walton, J.N., eds.), pp. 425-451, Churchill-Livingstone, Edinburgh. 

Figure 15-3. Overview of fatty acid metabolism showing the major pathways and end products. Ketone bodies comprise the substances acetoacetate, 3-hy-droxybutyrate, and acetone.

OHLROGGE J B (1994) Design of new plant products engineering of fatty acid metabolism. Plant Physiol. 104 821-6. 

As a hypothesis to explain his observations, Krugerl3 proposed (as is shown in scheme 3 along with other hypothesis) that the derived 3-ketonitrosamine underwent a cleavage reaction to yield a methylalkylnitrosamine and a carboxylic acid derivative, in analogy to fatty acid metabolism. 

The 3-ketothiolase has been purified and investigated from several poly(3HB)-synthesizing bacteria including Azotobacter beijerinckii [10], Ral-stonia eutropha [11], Zoogloea ramigera [12], Rhodococcus ruber [13], and Methylobacterium rhodesianum [14]. In R. eutropha the 3-ketothiolase occurs in two different forms, called A and B, which have different substrate specificities [11,15]. In the thiolytic reaction, enzyme A is only active with C4 and C5 3-ketoacyl-CoA whereas the substrate spectrum of enzyme B is much broader, since it is active with C4 to C10 substrates [11]. Enzyme A seems to be the main biosynthetic enzyme acting in the poly(3HB) synthesis pathway, while enzyme B should rather have a catabolic function in fatty-acid metabolism. However, in vitro studies with reconstituted purified enzyme systems have demonstrated that enzyme B can also contribute to poly(3HB) synthesis [15]. 

The deuteriated title compounds 9, 10 and 11 have been synthesized6 in multigram quantities in order to investigate the fatty acid metabolism in humans7-9 (equations 4-6). 

The authors have also synthesized134 fatty acids labelled with deuterium and carbon-11 in order to investigate if kinetic isotope effects related to fatty acid metabolism can be observed in vivo by pet133,135-137. In vitro, the large kinetic deuterium isotope effects are observed in the oxidation of deuteriated aliphatic carboxylic acids with alkaline permanganate and manganate135-139. 

DISEASES OF CARBOHYDRATE AND FATTY ACID METABOLISM IN MUSCLE 696... 

A second class of disorders of glycogen and fatty acid metabolism causes progressive weakness 699... 

One class of carbohydrate and fatty acid metabolism disorders is caused by defects in enzymes that function in the brain 703... 

The role of fatty acids as oxidizable fuels for brain metabolism is negligible, but ketone bodies, derived from fatty acid oxidation, can be utilized, particularly in the neonatal period. Diseases of carbohydrate and fatty acid metabolism may affect the brain directly or indirectly [1,10]. 

These agents activate PPAR-y a nuclear transcription factor important in fat cell differentiation and fatty acid metabolism. PPAR-yagonists enhance insulin sensitivity in muscle, liver, and fat tissues indirectly. Insulin must be present in significant quantities for these actions to occur. 

We will now draw attention to the Krebs cycle otherwise called the tricarboxylic acid cycle (fig. 17). It is now known that carbohydrate metabolism and fatty acid metabolism as well as acetate proceed via changes indicated in the cycle. The essential... 

Chenoweth believes that an explanation of the above results may lie in the reactions occurring before the entrance of fatty acid metabolites into the citric acid cycle. Activated acetate, i.e. acetyl coenzyme A (AcCoA) is the end-product of fatty acid metabolism prior to its condensation with oxalacetate to form citrate. Possibly fluoro-fatty acids behave like non-fluorinated fatty acids. The end-product before the oxalacetate condensation could be the same for all three fluorinated inhibitors, viz. fluoroacetyl coenzyme A (FAcCoA). Fluorocitrate could then be formed by the condensation of oxalacetate with FAcCoA, thereby blocking the citric acid cycle. The specificity of antagonisms must therefore occur before entrance of the metabolites into the citric acid cycle. 

Fatty acid metabolism Synthesis and degradation of ketone bodies... 

Scheme 2 shows the biosynthesis ofN-(3-oxooctanoyl)-L-homoserine lactone by Tral protein from Agrobacterium using 3-oxooctanoyl-ACP, derived from fatty acid metabolism, as a substrate [29, 33]. Recently, the first crystal structure of a LuxI protein homologue [34] has provided new insights into the function of AHL synthases which will aid the design of novel inhibitors of AHL biosynthesis. 

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