Homocysteic acid

R3Sn(IV)]4H2TPPS, (R = Me, Bu, Ph), respectively, in the solid state, are maintained in solution. Pentacoordination, in a Tbp configuration, eq-Rs, has been proposed for RsSnflV) derivatives of L-homocysteic acid on the basis of IR and Mossbauer spectroscopy The SO3 and NH3 groups of L-homocysteic acid are not involved in the coordination. 

Glutamic acid and its salts (especially the sodium salt) enhance the flavour of many convenience foods. Bejaars et al. (1996) described the determination of free glutamic acid in soups, meat products and Chinese food. The method involves hot water extraction of test portions followed by filtration and dilution. The extracts were treated with N,N-dimethyl-2-mercapto-ethyl-ammonium chloride and o-phtaldialdehyde to convert glutamic acid into a stable fluorescent, l-alkylthio-2-alkyhsoindole. Homocysteic acid was used as the internal standard. Separation was made on a Ci8 column, eluted with... 

Other neurotransmitters. The abundant glutamate, GABA, and glycine are major neurotransmitters. Do other amino acids also function in the brain Roles for L-aspartate and D-serine (p. 1785) have been identified, but it is very difficult either to discover or to disprove a neurotransmitter function for other amino acids. It is even more difficult for small amounts of various amines and small peptides that are present in the brain. Taurine (Fig. 24-25) is one of the most abundant free amino acids in animals and meets several criteria for consideration as both an inhibitory and an excitatory transmitter.797 798 However, its function is still uncertain (see Chapter 24). Homocysteic acid, formed by oxidation of homocysteine, is a powerful neuroexcitatory substance, but its concentration in the brain is very low.149 d-Aspartate is also present... 

Actually the irradiation chemistry of even simple amino acids and peptides is much more complex than these equations imply, and many other radiochemical products have been reported (13, 14, 49). These include glyoxylic acid, formaldehyde, hydrogen peroxide, carbon dioxide, succinic acid, aspartic acid, diaminosuccinic acid, methylamine, methane, dimethyl mercaptan, a-aminobutyric acid, methionine sulfoxide, methinonine sul-fone, methionine sulfoxime, homocysteic acid, and several unidentified nitrogen compounds (46, 51). 

Oxidized to Homocysteine sulphinic acid Homocysteic acid (Glutamic acid analogues) NMDA-Glu-R agonists excitotoxins]... 

Homocysteine or its metabolite homocysteic acid may have a direct neurotoxic effect in the developing neural tube both bind to the Ai-methyl-D-aspartate subtype of glutamate receptor. 

Sulfoxides are deoxygenated by BI3 NEt2Ph [23], Sulfides are also cleaved by BI3. Methionine reacts to yield a complex mixture of C-S bond-cleavage products, including homocysteic acid, homoserine, and homoserine lactone [24],... 

C4H9N05S DL-homocysteic acid 504-33-6 25.00 1.3624 2 4013 C4H11N03 tris(hydroxymethyl)methylamine 77-86-1 25.00 1.0382 2... 

Rosowski, A., Eorsch, R. A., Freisheim, J. H., Moran, R. G., Wick, M. Methotrexate analogues. 19. Replacement of the glutamate side chain in classical antifolates by L-homocysteic acid and L-cysteic acid effect on enzyme inhibition and antitumor activity. J. Med. Chem. 1984,27, 600-604. 

Davanger S, Torp R, Ottersen OP (1994a) Co-localization of glutamate and homocysteic acid immunoreactivities in human photoreceptor terminals. Neuroscience 65 123-133. 

Do KQ, Benz B, Sorg O, Pellerin L, Magistretti PJ (1997) fi-Adrenergic stimulation promotes homocysteic acid release from astrocyte cultures evidence for a role of astrocytes in the modulation of synaptic transmission. J Neurochem 68 2386-2394. 

Zhang N, Ottersen OP (1992) Differential cellular distribution of two sulphur-containing amino acids in rat cerebellum. An immunocytochemical investigation using antisera to taurine and homocysteic acid. Exp Brain Res 90 11-20. 

Cuenod M, Do KQ, Grandes P, Morino P, Streit P (1990) Localization and release of homocysteic acid, an excitatory sulfur-containing amino acid. J. Histochem. Cytochem., 38, 1713-1715. 

Studies on the inhibition of partially purified FPGS from human liver by the sulphonic acid analogues of MTX and AMT have also been reported [288]. The L-homocysteic acid analogues L-(VIII.IOO) and l-(VIII.102) had estimated K, values of 131 5 and 35 2 /iM, respectively, whereas the corresponding values for the L-cysteic acid analogues L-(VIII.lOl) and l-(VIII.103) were 173 + 6 and 66 5 pM. Interestingly, the kinetics of inhibition observed with the human enzyme were strictly competitive for l-(VIII. 100) and l-(VIII.102), but were of the mixed type for L-(VIII.lOl) and l-(VIII.103). While the latter... 

A novel coordination network of DJL,-homocysteic acid with strontium chloride was reported by Liu and coworkers [220]. This compound exhibited an infinite microporous multilayered structure, where chloride anions are intercalated between layers to neutralize the charge. TG and powder XRD showed that the layered structure of the compoimd, below 326 C, is sust ed in the process of the reversible loss/gain of coordinated water, confirming that the network involves a robust coordination-based cationic layer fimnework but rather... 

Methionine is not completely stable towards strong acid. A loss of 1274% by refluxing with 20% HCl for 20 h has been reported (Osono, 1955). The first decomposition product is homocysteine or homocystine (Osono et al., 1955). Homocysteic acid, aspartic acid, methionine sulfoxide, and methionine sulfone have also been identified as decomposition products (Pikkarainen and Kulonen, 1969) but oxidative processes were involved in these transformations. 

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