Of L-glutamic acid

In the 1950s, a group of coryneform bacteria which accumulate a large amount of L-glutamic acid in the culture medium were isolated (21). The use of mutant derivatives of these bacteria offered a new fermentation process for the production of many other kinds of amino acids (22). The amino acids which are produced by this method are mostiy of the T.-form, and the desired amino acid is singly accumulated. Therefore, it is very easy to isolate it from the culture broth. Rapid development of fermentative production and en2ymatic production have contributed to the lower costs of many protein amino acids and to their availabiUty in many fields as economical raw materials. 

An estimation of the amount of amino acid production and the production methods are shown ia Table 11. About 340,000 t/yr of L-glutamic acid, principally as its monosodium salt, are manufactured ia the world, about 85% ia the Asian area. The demand for DL-methionine and L-lysiae as feed supplements varies considerably depending on such factors as the soybean harvest ia the United States and the anchovy catch ia Pern. Because of the actions of D-amiao acid oxidase and i.-amino acid transamiaase ia the animal body (156), the D-form of methionine is as equally nutritive as the L-form, so that DL-methionine which is iaexpensively produced by chemical synthesis is primarily used as a feed supplement. In the United States the methionine hydroxy analogue is partially used ia place of methionine. The consumption of L-lysiae has iacreased ia recent years. The world consumption tripled from 35,000 t ia 1982 to 100,000 t ia 1987 (214). Current world consumption of L-tryptophan and i.-threonine are several tens to hundreds of tons. The demand for L-phenylalanine as the raw material for the synthesis of aspartame has been increasing markedly. 

The reaction is very slow in neutral solution, but the equiUbrium shifts toward the lactam rather than glutamic acid. Under strongly acidic or alkaline conditions, the ring-opening reaction requires a very short time (10). Therefore, neutralization of L-glutamic acid should be performed cautiously because intramolecular dehydration is noticeable even below 190°C. 

Glutamic acid dehydrogenase is widely distributed in microorganisms and higher plants as a catalyst in the synthesis of L-glutamic acid from a-ketoglutaric acid and free ammonia. Transaminase is contained in a wide variety of microorganisms. 

In the United States and some European countries, beet-sugar-waste molasses, or Stefen s waste, has been used as raw material for MSG production. The 2-pyrrohdinone-5-carboxyhc acid [98-79-3] contained ia beet sugar as by-product, is hydrolyzed at weakly alkaline pH, and moderate temperature (eg, pH 10.5—11.5, at 85°C for 2 h) to avoid racemization (14). The pH of the hydrolyzate is adjusted to 3.2 with a mineral acid to precipitate crystals of L-glutamic acid. The L-glutamic acid crystals obtained are transformed to MSG as described above. 

Microorganisms requite several minerals such as ferrous and potassium ions which play important roles in glutamic acid fermentation. Other important culture conditions include regulating aeration stirring. The biosynthesis of L-glutamic acid is performed under regulated aerobic conditions. 

Progress in fermentation technology has made it possible to raise the accumulation and the yield of L-glutamic acid above 100 g/L and 60% based on the total amount of sugar. AppHcation of genetic engineering techniques for further improvement is also in progress. 

An industrial fermentor of capacity up to several hundred kiloliters equipped with aeration and stirring devices, as well as other automatic control systems, is used. The cultures must be sterilized and aseptic air must be used owing to the high sensitivity to bacterial contamination of L-glutamic acid fermentation. 

Another viable method for the synthesis of L-foUc acid (1) starts from 6-formylpterin (23). The diester of L-glutamic acid (24) is condensed with 6-formylpterin (23). Reduction of the Schiff base with sodium borohydride is followed by hydrolysis to yield L-foUc acid (37). 

Such enzymes catalyse the condensation of specific compounds, accompanied by the breakdown of a pyrophosphate bond in adenosine triphosphate (10.64). Adenosine is the condensation product of a pentose (D-ribofuranose) and a purine (adenine). Scheme 10.15 shows the action of glutamine synthetase on a mixture of L-glutamic acid (10.65) and... 

The latter, ester-type derivatives (21) were prepared by the reaction of L-glutamic acid with hydroxyethyl derivatives of nucleic acid bases. The reaction was studied in the presence of p-toluenesulfonic acid at 100-110°C in dioxane, and water formed was removed by azeotropic distillation with dioxane ( ). 

Mansour, M., Thaller, S., andKorte, F. Action of sunlight on parathion. Bull. Environ. Contam. Toxicol, 30(3) 358-364,1983. Manzurola, E. and Apelblat, A. Solubilities of L-glutamic acid, 3-nitrobenzoic acid, p-toluic acid, calcium-L-lactate, calcium gluconate, magnesium-DL-aspartate, and magnesium-L-lactate in water, J. Chem. Thermodyn., 34 (7) 1127-1136, 2002. Maraqa, M.A., Zhao, X., Wallace, R.B., and Voice, T.C. Retardation coefficients of nonionic organic compounds determined by batch and column techniques. Soil Sci. Soc. Am. J., 62(1) 142-152, 1998. 

The solvent-mediated transformation of o -L-glutamic acid to the S-form was quantitatively monitored over time at a series of temperatures [248]. The calibration model was built using dry physical mixtures of the forms, but still successfully predicted composition in suspension samples. Cornel et al. monitored the solute concentration and the solvent-mediated solid-state transformation of L-glutamic acid simultaneously [249]. However, the authors note that multivariate analysis was required to achieve this. Additionally, they caution that it was necessary to experimentally evaluate the effect of solid composition, suspension density, solute concentration, particle size and distribution, particle shape, and temperature on the Raman spectra during calibration in order to have confidence in the quantitative results. This can be a substantial experi-... 

T. Ono, J.H. ter Horst and P.J. Jansens, Quantitative measurement of the polymorphic transformation of L-glutamic acid using in-situ Raman spectroscopy, Cryst. Growth Des., 4, 465-469 (2004). 

Commons K, Valentio R (2002) Cellular basis of substance P in the periaqueductal gray and dorsal raphe nucleus. J Comp Neurol 447 82-97 Conti L, Pinder R (1979) A controlled comparative trial of mianserin and diazepam in the treatment of anxiety states in psychiatric outpatients. J Int Med Res 7 185-189 Coyle J, Leski M, Morrison J (2002) The diverse roles of L-glutamic acid in brain signal transduction. In Davis K, Charney D, Coyle J, Nemeroff C (eds) Neuropsychopharmacology and the fifth generation of progress. Lippincott Williams and Wilkins, Philadelphia, pp 71-90... 

Thermal and charge induced random coil to a-helix transitions of polyll-glutamic acid) (PGA) are measured by optical rotatory dispersion in various solvents. The data of PGA in 0.1 M NaCI are analyzed by the Zimm-Rice theory. The initiation parameter, o, of the Zimm-Rice theory is given by a value of 5 ( 1) x 10 3. Random copolymers of L-glutamic acid and L-alanine containing 10, 30, and 40 molar percents of alanyl residue are analyzed as well. 

Exercise 25-18 The tripeptide, eisenine, has only one free carboxyl group, does not react with 2,4-dinitrofluorobenzene, and on complete hydrolysis yields 2 moles of L-glutamic acid, 1 mole of L-alanine, and 1 mole of ammonia. Alanine is indicated to be the C-terminal amino acid. Write a structure for eisenine that is in accord with the above facts. 

Puchades, R., Lemieux, L., and Simard, R. E. (1989). Sensitive, rapid and precise determination of L-glutamic acid in cheese using a flow injection system with immobilized enzyme column. /. Food Sci. 54, 423M26. 

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