Pyruvate family

Amino Acid Biosynthesis Aromatic amino acid family Aspartate family Glutamate family Pyruvate family Serine family Histidine family Other... 

Sulfate Must Be Reduced to Sulfide before Incorporation into Amino Acids The Aspartate and Pyruvate Families Both Make Contributions to the Synthesis of Isoleucine... 

The aspartate (oxaloacetate) family of amino acids includes aspartate, asparagine, methionine, lysine, threonine, and isoleucine (see fig. 21.1). The pyruvate family includes alanine, valine, leucine, and also lysine and isoleucine (see fig. 21.1). Threonine is a precursor of isoleucine. It is converted into isoleucine by a group of enzymes that are also used in the synthesis of valine (fig. 21.10). 

The aspartate and pyruvate families together contain 11 amino acids. Because of the reactions involved in its synthesis, isoleucine is considered a member of both families. Isoleucine and valine use four enzymes in common in their biosynthetic pathways. 

The aspartate family also contains asparagine, lysine, methionine, and threonine. Threonine contributes to the reaction pathway in which isoleucine is synthesized. The synthesis of isoleucine, often considered to be a member of the pyruvate family, is discussed on p. 467. 

THE PYRUVATE FAMILY The pyruvate family consists of alanine, valine, leucine, and isoleucine. Alanine is synthesized from pyruvate in a single step ... 

Valine (val), alanine (ala), and leucine (leu) are members of the pyruvate family. 

Classification of amino acids into biosynthetic families emphasizes the common origin of related metabolites and is conceptually useful in delineating regulatory relationships. Lysine, threonine, methionine, and isoleucine comprise a family of amino acids originating with aspartate. However, isoleucine is also structurally and metabolically related to the branched-chain amino acids, leucine and valine. The latter two amino acids, along with alanine, are members of the pyruvate family. The common metabolic pre-... 

Fig.3. Amino acids. The pyruvate family of amino acids...

The pyruvate family is derived from pyruvate and oxaloacetate (Fig. 3) ... 

Further metabolism of amino acids produced by transamination results in the formation of biogenetically related families of amino acids. Thus the pyruvate family comprises alanine, leucine and valine and similar families are based upon aspartic and glutamic acids and serine. 

Salzer et al. prepared a set of planar-chiral diphosphine ligands based on the arene chromium tricarbonyl backbone (Fig. 36.3) [21]. The straightforward four-step synthetic route allowed the preparation of 20 ligands of this family. These ligands were tested in Ru- and Rh-catalyzed enantioselective hydrogenation of various substrates, including the standard C=C substrates (dimethyl itaconate, methyl-2-acetamidocinnamate, methyl-2-acetamidoacrylate) as well as MEA-imine (l-(methoxymethyl)ethylidene-methylethylaniline) and ethyl pyruvate. Moderate conversions and ee-values were obtained. 

Non-essential amino acids are those that arise by transamination from 2-oxoacids in the intermediary metabolism. These belong to the glutamate family (Glu, Gin, Pro, Arg, derived from 2-oxoglutarate), the aspartate family (only Asp and Asn in this group, derived from oxaloacetate), and alanine, which can be formed by transamination from pyruvate. The amino acids in the serine family (Ser, Gly, Cys) and histidine, which arise from intermediates of glycolysis, can also be synthesized by the human body. 

Malic enzyme (malate dehydrogenase (decarboxylating), EC 1.1.1.39) catalyzes reversible oxidative decarboxylation of malate to pyruvate. The enzyme uses NAD+ as an electron acceptor, but it is also able to utilize NADP+ with lower affinity (Drmota et al. 1996). With a subunit size of approximately 63 kDa, the Trichomonas hydrogenosomal malic enzyme belongs to the family of large, eukaryotic type of malic enzymes. In contrast, the approximately 40-kDa-subunit malic enzyme, located in the cytosol, belongs... 

Dehydrogenases often act primarily to reduce a carbonyl compound rather than to dehydrogenate an alcohol. These enzymes may still be called dehydrogenases. For example, in the lactic acid fermentation lactate is formed by reduction of pyruvate but we still call the enzyme lactate dehydrogenase. In our bodies this enzyme functions in both directions. However, some enzymes that act mainly in the direction of reduction are called reductases. An example is aldose reductase, a member of a family of aldo-keto reductases71 73 which have (a / P)8-barrel structures.74 76... 

Alkaloids from tryptophan. The alkaloid harmine, which is found in several families of plants, can be formed from tryptophan and acetaldehyde (or pyruvate) in the same manner as is indicated for the formation of papaverine in Fig. 25-10. Some other characteristic plant metabolites such as psilocybine, an hallucinogenic material from the mushroom... 

Outline of the biosynthesis of the 20 amino acids found in proteins. The de novo biosynthesis of amino acids starts with carbon compounds found in the central metabolic pathways. The central metabolic pathways are drawn in black, and the additional pathways are drawn in red. Some key intermediates are illustrated, and the number of steps in each pathway is indicated alongside the conversion arrow. All common amino acids are emphasized by boxes. Dashed arrows from pyruvate to both diaminopimelate and isoleucine reflect the fact that pyruvate contributes some of the side-chain carbon atoms for each of these amino acids. Note that lysine is unique in that two completely different pathways exist for its biosynthesis. The six amino acid families are screened. 

The majority of useful lyase families utilize anionically functionalized substrates such as pyruvate or dihydroxyacetone phosphate which remain unaltered during catalysis. The charged group thereby introduced into the products (phosphate, carboxylate) not only constitutes a handle for binding of the substrates by the enzymes but also can facilitate the preparative isolation from... 

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