Carbon compounds oxoacids

A major aim of amino acid catabolism is removal of the a-NH2 group, which results in the formation of ammonia which is then converted to urea. The removal of the a-NH2 group for most amino acids results in the formation of a carbon-compound, which is usually an oxoacid (e.g. the oxoacid for alanine is pyruvate). 

Hydroxides MOH are important compounds for all the alkali metals. They can easily formed by reaction of oxides with water (or atmosphere moisture). They are soluble in water and give strong base. Compounds of oxoacids are commonly encountered, such as carbonate, nitrate, sulphate, etc. as these anions are fairly large, lithium compounds tend to be the most soluble in the series. Many of these compounds crystallise in a variety of hydrated forms (e.g. Na2C03. H2 O with n = 1, 7 or 10). 

Biomimetic Synthesis of Solerone. We applied pyruvate decarboxylase [EC 4.1.1.1] (PDC) as key enzyme for the biomimetic synthesis elucidating the formation of solerone 1 figure 1). The thiamine diphosphate depending enzyme from Saccharomyces cerevisiae is responsible for the decarboxylation of pyruvate in the course of alcoholic fermentation. After loss of carbon dioxide from 2-oxoacids the resulting aldehyde is released. Alternatively, the cofactor-bound decarboxylation product can react with a further aldehyde. By the latter acyloin condensation a new carbon-carbon bond will be formed, thus opening a biosynthetic way to a-hydroxy carbonyl compounds 11J2). 

Mono and dioxygenase are employed extensively by bacteria in the degradation of aromatic compounds and are therefore fundamentally important in the carbon cycle of the biosphere. See 2-Oxoacid dioxygenases. 

Another important group of reactions are those in which the hydrocarbon chain of the alkoxyl radicals cleaves to form low molecular weight products, mainly volatile and sensory active compounds. The cleavage takes place on both sides of the alkoxyl radicals (Figure 3.45). The composition of reaction products formed from alkoxyl radicals derived from unsaturated fatty acids depends on which carbon, next to the hydroperoxide group, the double bond is located. In addition to non-volatile oxoacids and hydroxy acids. 

Acyl CoA synthetase synthesises, in the presence of HS-CoA, acyl-CoA from a saturated fatty acid. Acyl CoA is transformed by acyl-CoA dehydrogenase into 2,3-dehydroacyl-CoA, and isomerism leads to trhydroxyacyl dehydrogenase the latter compound is hydrolysed by 3-ketoacyl-CoA thiolase to HS-CoA and 3-oxoacid. This acid eliminates carbon dioxide and yields methylketone, with catalysis of decarboxylase. Reductase can reduce methylketone to a secondary alcohol. 

Surprisingly, very few compounds with higher-coordinated silicon atoms and mineral oxoacids such as carbonic, nitric, phosphoric, and sulfuric acids are known. These involve oxygen-coordination which is - on the other hand - very common. An example is compound 81 (Scheme 18) in which the carbonate ion is generated from carbon dioxide. Recently, an unusual higher-coordinated molecular silicon... 

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