Glutamic acid conversion

Folic acid is synthesized both in microorganisms and in plants. Guanosine-5-ttiphosphate (GTP) (33), -aminobenzoic acid (PABA), and L-glutamic acid are the precursors. Reviews are available for details (63,64). The sequence of reactions responsible for the enzymatic conversion of GTP to 7,8-dihydrofohc acid (2) is shown. 

In E. coli GTP cyclohydrolase catalyzes the conversion of GTP (33) into 7,8-dihydroneoptetin triphosphate (34) via a three-step sequence. Hydrolysis of the triphosphate group of (34) is achieved by a nonspecific pyrophosphatase to afford dihydroneopterin (35) (65). The free alcohol (36) is obtained by the removal of residual phosphate by an unknown phosphomonoesterase. The dihydroneoptetin undergoes a retro-aldol reaction with the elimination of a hydroxy acetaldehyde moiety. Addition of a pyrophosphate group affords hydroxymethyl-7,8-dihydroptetin pyrophosphate (37). Dihydropteroate synthase catalyzes the condensation of hydroxymethyl-7,8-dihydropteroate pyrophosphate with PABA to furnish 7,8-dihydropteroate (38). Finally, L-glutamic acid is condensed with 7,8-dihydropteroate in the presence of dihydrofolate synthetase. 

The best results were obtained with L-aspartic add as the amino donor for P. denitrificam and phenylpyruvic add as the amino acceptor. With L-aspartic add, conversion of phenylpyruvic add exceeded 90%. This may be attributed to absence of feedback inhibition of the reaction due to metabolism of file reaction product, oxaloacetic add. When using glutamic acid the conversion of phenylpyruvic add did not exceed 60%. 

Blout ER, Idelson M (1956) Polypeptides VI. Poly-alpha-glutamic acid preparation and helix-coil conversions. J Am Chem Soc 78 497-498... 

Vitamin Ba (pyridoxine, pyridoxal, pyridoxamine) like nicotinic acid is a pyridine derivative. Its phosphorylated form is the coenzyme in enzymes that decarboxylate amino acids, e.g., tyrosine, arginine, glycine, glutamic acid, and dihydroxyphenylalanine. Vitamin B participates as coenzyme in various transaminations. It also functions in the conversion of tryptophan to nicotinic acid and amide. It is generally concerned with protein metabolism, e.g., the vitamin B8 requirement is increased in rats during increased protein intake. Vitamin B6 is also involved in the formation of unsaturated fatty acids. 

It seems likely to the author, if not certain, that individual human beings and individual experimental animals possess substantial quantitative differences with respect to their utilization of glutamic acid and the conversion of other nonessential amino acids into glutamic acid, and vice versa. If this is the case, it could well be that certain... 

Glutamic Acid.—The greater part of the glutamic acid is isolated as hydrochloride before the mixture of amino acids is esterified. It is contained with aspartic acid ester in the aqueous solution after the phenylalanine ester has been extracted by ether, and it is separated from aspartic acid, after hydrolysis by baryta, by conversion into its hydrochloride from this it is obtained by treatment with the calculated quantity of soda to combine with the hydrochloric acid and by crystallisation from water, in which it is soluble with some difficulty. 

Aspartic Acid.—A portion of the aspartic acid, after separation from phenylalanine ester and after hydrolysis by baryta, may separate as barium salt this is the barium salt of racemic aspartic acid. The remainder is isolated, when the glutamic acid has been removed as hydrochloride, by boiling with lead hydroxide and treating with hydrogen sulphide to remove hydrochloric acid and lead respectively, and by crystallising from water. It maybe characterised by conversion into its copper salt, or by analysis, and is estimated by its weight. 

L B. Warfarin does not produce an anticoagulant effect in vitro. It inhibits coagulation of blood only in vivo, because the effect depends upon warfarin s effect in the liver on the production of clotting factors. Warfarin does not require conversion into an active drug. It inhibits the post-ribosomal carboxy-lation of glutamic acid residues in the vitamin K-dependent clotting factors. Therefore, heparin rather than warfarin is used when blood is collected from donors and stored. 

In addition to the isomerization of glutamic acid, several other coenzyme B12-catalyzed reactions have now been discovered (I, 9, 15, 31, 51). The conversion of methylmalonic acid to succinic acid is very similar, and has been shown to occur through the migration of a carboxyl group, and postulated to involve free radical itermediates, as follows (15) ... 

The (R)-enantiomer of (242) has also been prepared and used as a chiral auxiliary in an enantioselective aldol synthesis of (+)-(S )-gingerol (79CB3703). (R )-Glutamic acid (246) was thus converted into (i )-pyroglutamic acid by simply heating in water. Conversion of (247) to its methyl ester and LAH reduction delivered alcohol (248). Ethyl nitrite treatment of (248) gave nitrosoamine (249), which was methylated to furnish (250). Exposure of (250) to LAH completed the synthesis of the required chiral auxiliary RAMP [(R)- l-amino-2-(methoxymethyl)pyrrolidine]. The hydrazone (252), derived from RAMP and acetone, was... 

Since in the citric acid cycle there is no net production of its intermediates, mechanisms must be available for their continual production. In the absence of a supply of oxalacetic acid, acctaic" cannot enter the cycle. Intermediates for the cycle can arise from the carinxylation of pyruvic acid with CO, (e.g., to form malic acid), the addition of CO > to phosphcnnlpyruvic acid to yield oxalacetic acid, the formation of succinic acid from propionic acid plus CO, and the conversion of glutamic acid and aspartic acid to alpha-ketoglutaric acid and oxalacetic acid, respectively. See Fig. 3. 

Deamination 17 Examples of deamination and decarboxylation include conversion of amino acids to fusel oil (leucine to isoamyl alcohol, isoleucine to amyl alcohol, and phenylalanine to phenyl ethanol). Fusel oil formation is a normal function of all yeast fermentations (in alcoholic beverages, levels range from trace to 2200 parts per million). Deamination Glutamic acid to gamma-OH-butyric acid (S. cerevisiae). 

Abderhalden and Kautzch (77) reported that the heating of dry glutamic acid to 180°-200° led to the formation of essentially optically inactive pyrrolidone carboxylic acid. They obtained optically active l-pyrrolidone carboxylic acid by heating L-glutamic acid at 150°-160° followed by fractional crystallization of the product. These workers also observed that treatment of optically active pyrrolidone carboxylic acid with strong mineral acid led to its conversion to optically active glutamic... 

Wilson and Cannan (18) reported detailed observations on the equilibrium and velocity constants in the glutamic acid—pyrrolidone carboxylic acid system in dilute aqueous solution. They found that the conversion of glutamic acid to pyrrolidone carboxylic acid follows the equation for a reversible first-order reaction. The equilibrium constant and the rate at which the equilibrium is achieved depend on the pH of the solution and the temperature. In neutral solutions, the equilibrium favors almost complete conversion of glutamic acid to pyrrolidone carboxylic acid however, the rate of the reaction is very slow and thus only 1% conversion occurs after 2-3 hr at 100°. In weakly acid (pH 4) and alkaline (pH 10) solutions, the conversion of glutamic acid to pyrrolidone carboxylic acid is much faster and about 98% conversion occurs in less than 60 hr. In strong acid (2 N HC1) and base (0.5 N NaOH) the conversion of pyrrolidone carboxylic acid to glutamic acid proceeds rapidly and virtually to completion. Other studies have shown that the conversion of glutamic acid to pyrrolidone carboxylic acid can be carried out within 2 hr at 142° with little alteration of optical rotation (80). 

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