Aspartate biosynthesis

The common mechanism of aspartate biosynthesis is analogous to that of alanine synthesis, as either oxaloacetate [Eq. (3)] or pyruvate [Eq. (1)] would... 

Fia. 2. Schematic representation of pathways for arginine, urea, and carbamyl aspartate biosynthesis. 

Aspartic acid decarboxylase cataly2es the decarboxylation of asparatic acid to yield P-alanine (10), a precursor for the biosynthesis of pantothenic acid (67). FiaaHy, (R)-pantothenic acid is obtaiaed by coupling P-alaniae (10) with (R)-pantoate (22) ia the presence of pantothenate synthetase ... 

One of the steps in the biosynthesis of uridine monophosphate is the reaction of aspartate with carbamoyl phosphate to give carbamoyl aspartate followed by cyclization to form dihydroorotate. Propose mechanisms for both steps. 

Pyridoxamine phosphate serves as a coenzyme of transaminases, e.g., lysyl oxidase (collagen biosynthesis), serine hydroxymethyl transferase (Cl-metabolism), S-aminolevulinate synthase (porphyrin biosynthesis), glycogen phosphoiylase (mobilization of glycogen), aspartate aminotransferase (transamination), alanine aminotransferase (transamination), kynureninase (biosynthesis of niacin), glutamate decarboxylase (biosynthesis of GABA), tyrosine decarboxylase (biosynthesis of tyramine), serine dehydratase ((3-elimination), cystathionine 3-synthase (metabolism of methionine), and cystathionine y-lyase (y-elimination). 

Much less is known about the participation of sugars in the biosynthesis of pyramine in yeasts, and although it has been proven that sugars can provide some carbon atoms, the exact nature of the more advanced intermediates of sugar origin is not yet clear. Some features of the biosynthesis in S. cerevisiae are summarized in Scheme 33. Two l5N atoms from DL-(l,3-,5N2)histidine were incorporated into the N-3 and amino nitrogen atoms of pyramine. The nitrogen atom of (,5N)aspartate, a known precursor of N-l of histidine, was incorporated into pyramine without dilution.58-70 It was also found that N-l and C-2 of pyramine came respectively from N-l and C-2 of pyridoxol.71-73... 

Aspartate transcarbamoylase (ATCase), the catalyst for the first reaction unique to pyrimidine biosynthesis (Figure 34-7), is feedback-inhibited by cytidine tri-... 

Since biosynthesis of IMP consumes glycine, glutamine, tetrahydrofolate derivatives, aspartate, and ATP, it is advantageous to regulate purine biosynthesis. The major determinant of the rate of de novo purine nucleotide biosynthesis is the concentration of PRPP, whose pool size depends on its rates of synthesis, utilization, and degradation. The rate of PRPP synthesis depends on the availabihty of ribose 5-phosphate and on the activity of PRPP synthase, an enzyme sensitive to feedback inhibition by AMP, ADP, GMP, and GDP. 

Palaiologos, G., Hertz, L. and Schousboe, A. Evidence that aspartate aminotransferase activity and ketodicarboxylate carrier function are essential for biosynthesis of transmitter glutamate. /. Neurochem. 51 317-320,1988. 

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

Sterol biosynthesis Bile acid biosynthesis C2rSteroid hormone metabolism Androgen and estrogen metabolism Nucleotide Metabolism Purine metabolism Pyrimidine metabolism Nucleotide sugar metabolism Amino sugar metabolism Amino Acid Metabolism Glutamate metabolism Alanine and aspartate metabolism Glycine, serine, and threonine metabolism... 

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. 

GatCAB amidotransferase.This natural product mimics the charged 3 -terminus of aa-tRNA and has been used as a tool for the study of protein biosynthesis. The parent compound 22 is a very weak inhibitor of AdT. The amino acid chain is related to tyrosine and differs from the glutamic and aspartic side chains transformed in the kinase or the transamidase steps. Replacement of the methoxyphenyl moiety of puromycin by carboxylic acid derivatives (23-26) improved the ability to inhibit this AdT. Stable analogues of the transition state in the last step of the transamidation process (27-29) where the carbonyl to be attacked by NH3 is replaced by tetrahedral sulfur or phosphorus atom with a methyl group mimicking ammonia exhibited the highest activity. 

L. J. Reitzer, Ammonia Assimilation and the Biosynthesis of Glutamine, Glutamate, Aspartate, Asparagine, L-alanine, and D-alanine. In Escherichia coll and Salmonella, Cellular and Molecular Biology F. C. Neidhardt, Ed. ASM Press Washington, DC, 1996 Vol. 1, pp 391 07. 

Serine (Ser or S) ((S)-2-amino-3-hydroxypropanoic acid) is a polar, neutral, uncharged amino acid with the formula H00CCH(NH2)CH20H. It has an aliphatic hydroxyl side chain and can be seen as a hydroxylated version of Ala. Ser participates in the biosynthesis of purines and pyrimidines and is also the precursor to several amino acids including Gly, Cys, and Trp (in bacteria). In addition, it is the precursor to numerous other metabolites, including sphingolipids and is present in enzymes such as a-chymotrypsin. Ser, Asn, and aspartate disrupt a helices. 

Wu S-P, Wu G, Surerus KK, Cowan JA. 2002c. Iron-sulfur cluster biosynthesis Kinetic analysis of [2Fe-2S] cluster transfer from holo ISU to apo Fd Role of redox chemistry and a conserved aspartate. Biochemistry 41 8876-85. 

ATCase catalyzes the first step in the biosynthesis of cytidine triphosphate (CTP). The sequence of reactions leading from the reactants, aspartate and carbamoyl phosphate, to CTP is shown in Fig. 8.19. 

As the first committed step in the biosynthesis of AMP from IMP, AMPSase plays a central role in de novo purine nucleotide biosynthesis. A 6-phosphoryl-IMP intermediate appears to be formed during catalysis, and kinetic studies of E. coli AMPSase demonstrated that the substrates bind to the enzyme active sites randomly. With mammalian AMPSase, aspartate exhibits preferred binding to the E GTPTMP complex rather than to the free enzyme. Other kinetic data support the inference that Mg-aspartate complex formation occurs within the adenylosuccinate synthetase active site and that such a... 

Although L-phenylalanine is a protein amino acid, and is known as a protein acid type of alkaloid precursor, its real role in biosynthesis (providing C and N atoms) only relates to carbon atoms. L-phenylalanine is a part of magic 20 (a term deployed by Crick in his discussion of the genetic code) and just for this reason should also be listed as a protein amino acid type of alkaloid precursor, although its duty in alkaloid synthesis is not the same as other protein amino acids. However, in relation to magic 20 it is necessary to observe that only part of these amino acids are well-known alkaloid precursors. They are formed from only two amino acid families Histidine and Aromatic and the Aspartate family . 

The pyrimidine antagonists inhibit the biosynthesis of pyrimidine nucleotides or interfere with vital cellular functions, such as the synthesis or function of nucleic acids. The analogues of deoxycytidine and thymidine that are used are inhibitors of DNA synthesis while 5-fluorouracil (5-FU) an analogue of uracil, is an inhibitor of both RNA function and of the synthesis of thymidylate (see Fig. 2). PALA (N-phosphonoacetyl-L-aspartate), an inhibitor of as-... 

Aspartic acid and arginines are important substrates for the biosynthesis of purine bases. They are also glycosylation sites in proteins. These reasons have been at the origin of the synthesis of their mono and difluoro analogues. 

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