Biosynthesis from glutamic acid

Vogel discovered an alternate pathway of ornithine biosynthesis from glutamic acid involving AT-acetylglutamate 114, 116). He has obtained evidence that this is the major pathway for ornithine formation in E. colt and Neurospora 127). The pathway shown in Fig. 5 is of minor importance for ornithine biosynthesis but is the major one for proline. These conclusions have been substantiated by isotope competition experiments 128). The steps in the acetylglutamate pathway is shown in Fig. 6. 

Nevertheless the biosynthesis of glutamine proceeds from glutamic acid The dif ference is that the endergonic process m Equation 1 is coupled with the strongly exer gome hydrolysis of ATP... 

The Wolff rearrangement and the Arndt-Eistert homologation sequence are very useful in organic synthesis. One of the most popular applications involves amino acids. An interesting example has been described as a key reaction in the synthesis of a 14C-labeled amino acid used for deciphering the biosynthesis of penicillin N from glutamic acid (Scheme 3.2).9 This rearrangement proceeds without racemization and can thus be applied in peptide synthesis. 

Wurz, R. E. M., Kepner, R. E., Webb, A. D. (1988) The biosynthesis of certain gamma-lactones from glutamic acid by film yeast activity on the surface of Flor Sherry. American Journal of... 

C. HMG CoA is not formed from glutamic acid, but from acetyl CoA and acetoacetyl CoA. It is also formed by degradation of leucine in muscle. It is cleaved to form acetyl CoA and the ketone body acetoacetate. It is reduced to mevalonic acid in cholesterol biosynthesis. 

Fig. I. A scheme presenting the biosynthesis of ornithine from glutamic acid and the ornithine cycle. The various reactions are numbered. The enzymes and the reactions they catalyze are listed in Table I. The structures are presented (without naming compounds) to enable the reader to visualize the transformations. The characteristics of the enzymatic reactions are discussed in the text.

Glutamine is synthesized in pigeon liver homogenates from glutamic acid and ammonia. The reaction requires ATP and a specific enzyme, glutamine synthetase. ADP is formed and inorganic phosphate is released in the reaction. The mechanism of the reaction is similar to that involved in glutathione biosynthesis. 

Ornithine Biosynthesis. Two reaction sequences leading to ornithine synthesis from glutamic acid have been described. In Neurospora and the yeast Tondopsis utilis the sequence involves the simple transamination of glutamic semialdehyde (IV). The reaction proceeds much... 

The biosynthesis of glutamine from glutamic acid and NH3 by enzyme preparations from liver and brain has been shown to require ATP and magenesium (1, 2). It has been found further that hydroxylamine can be substituted for NHs, resulting in the formation of glutamohydroxamic... 

Quite another pathw ay has been show n to be follow-ed in the biosynthesis of ornithine from glutamic acid, namehq via A -acetylglutamic acid, iV-acetylglutamic semialdehyde and A "-acetylornithine.""" This leads to the reaction sequence showm below. ... 

Fig. 66 (Davis)—Biosynthesis of arginine from glutamic acid.

The contribution of theanine to the taste of green tea is discussed. Theanine biosynthesis occurs in the plant roots from glutamic acid and ethy-... 

L Glutamic acid is not an essential ammo acid It need not be present m the diet because animals can biosynthesize it from sources of a ketoglutaric acid It is however a key intermediate m the biosynthesis of other ammo acids by a process known as transamination L Alanine for example is formed from pyruvic acid by transamination from L glutamic acid... 

There is only a small selection of nonprotein amino acids that contain carbonyl groups in the form of ketone, aldehyde, and carboxylic acid moieties, as part of the side chain. The examples given in Table 6 are components of nonribosomal peptides isolated from bacteria or fungi and siderophores from bacteria. The biosynthesis of these amino acids is not clear however, some of the amino acids with carboxylic acid side chains may be traced back to the L-a-amino acids aspartic acid and glutamic acid. 

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