Editing Glutamic acid (section)

===Optical isomerism===
Glutamic acid is [[chiral]]; two mirror-image [[Enantiomer|enantiomers]] exist: {{sm|d}}(−), and {{sm|l}}(+). The {{sm|l}} form is more widely occurring in nature, but the {{sm|d}} form occurs in some special contexts, such as the [[bacterial capsule]] and [[cell wall]]s of the [[bacteria]] (which produce it from the {{sm|l}} form with the [[enzyme]] [[glutamate racemase]]) and the [[liver]] of [[mammals]].<ref name=Dglut>National Center for Biotechnology Information, "[https://pubchem.ncbi.nlm.nih.gov/compound/23327 D-glutamate]". ''PubChem Compound Database'', CID=23327. Accessed 2017-02-17.</ref><ref name=DgEcoli>{{cite journal | last1 = Liu | first1 = L. | last2 = Yoshimura | first2 = T. | last3 = Endo | first3 = K. | last4 = Kishimoto | first4 = K. | last5 = Fuchikami | first5 = Y. | last6 = Manning | first6 = J. M. | last7 = Esaki | first7 = N. | last8 = Soda | first8 = K. | year = 1998 | title = Compensation for {{sc|D}}-glutamate auxotrophy of ''Escherichia coli'' WM335 by {{sc|D}}-amino acid aminotransferase gene and regulation of ''murI'' expression | journal = Bioscience, Biotechnology, and Biochemistry | volume = 62 | issue = 1 | pages = 193–195 | doi = 10.1271/bbb.62.193 | pmid = 9501533 | doi-access = free }}</ref>
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{{sm|d}}-glutamate is also present in certain foods e.g., soybeans and also arises from the turnover of the intestinal tract microflora, whose cell walls contain significant {{sm|d}}-glutamate. Unlike other {{sm|d}}-amino acids, {{sm|d}}-glutamate is not oxidized by the {{sm|d}}-amino acid oxidases, and therefore this detoxification pathway is not available for handling {{sm|d}}-glutamate. Likewise, {{sm|d}}-glutamic acid, when ingested, largely escapes most deamination reactions (unlike the {{sm|l}}-counterpart). Free {{sm|d}}-glutamate is found in mammalian tissue at surprisingly high levels, with {{sm|d}}-glutamate accounting for 9% of the total glutamate present in liver. {{sm|d}}-glutamate is the most potent natural inhibitor of glutathione synthesis identified to date and this may account for its localization to the liver, since circulating {{sm|d}}-glutamate may alter redox stability ({{cite journal | pmid = 11158923 | volume=280 | title=Regulatory responses to an oral D-glutamate load: formation of D-pyrrolidone carboxylic acid in humans | year=2001 | journal=Am J Physiol Endocrinol Metab | pages=E214-20  | last1 = Raj | first1 = D | last2 = Langford | first2 = M | last3 = Krueger | first3 = S | last4 = Shelton | first4 = M | last5 = Welbourne | first5 = T | doi = 10.1152/ajpendo.2001.280.2.e214}}). Certain eels are known to use {{sm|d}}-glutamic acid as a pheromone for chemical communication.-->