Aspartic acid, oxidation

Fig. 3. Cation-exchange chromatography of protein standards. Column poly(aspartic acid) Vydac (10 pm), 20 x 0.46 cm. Sample 25 pi containing 12.5 pg of ovalbumin and 25 pg each of the other proteins in the weak buffer. Flow rate 1 ml/min. Weak buffer 0.05 mol/1 potassium phosphate, pH 6.0. Strong buffer same +0.6 mol/1 sodium chloride Elution 80-min linear gradient, 0-100% strong buffer. Peaks a = ovalbumin, b = bacitracin, c = myoglobin, d = chymotrypsinogen A, e = cytochrom C (reduced), / = ribonuclease A, g = cytochrome C (oxidised), h = lysozyme. The cytochrome C peaks were identified by oxidation with potassium ferricyanide and reduction with sodium dithionite [47]...

Grb-2 facilitates the transduction of an extracellular stimulus to an intracellular signaling pathway, (b) The adaptor protein PSD-95 associates through one of its three PDZ domains with the N-methyl-D-aspartic acid (NMDA) receptor. Another PDZ domain associates with a PDZ domain from neuronal nitric oxide synthase (nNOS). Through its interaction with PSD-95, nNOS is localized to the NMDA receptor. Stimulation by glutamate induces an influx of calcium, which activates nNOS, resulting in the production of nitric oxide. 

In the published synthesis the ozonolysis is performed on the protected product (9) and aldehyde (10) isolated before oxidation, hydrolysis and decarboxylation give aspartic acid. 

Langsetmo K, Fuchs JA, Woodward C (1991) The conserved, buried aspartic acid in oxidized Escherichia coli thioredoxin has a pKa of 7.5. its titration produces a related shift in global stability Biochemistry 30 7603-7609. 

A number of P-chirogenic diaminophosphine oxides (DIAPHOXs) 275 derived from aspartic acid were prepared via hydrolysis of triaminophosphine intermediate 274, generated in a fully diastereoselective reaction of triamines 273 with phosphorus trichloride (Scheme 65) [102, 103],... 

H. Yokoyama, N. Mori, N. Kasai, T. Matsue, I. Uchida, N. Kobayashi, N. Tsuchihashi, T. Yoshimura, M. Hiramatsu, and S.I. Niwa, Direct and continuous monitoring of intrahippocampal nitric oxide (NO) by an NO sensor in freely moving rat after N-methyl-D-aspartic acid injection. Denki Kagaku 63, 1167-1170 (1995). 

Figures 11(a) and 11(b) [112] show the variation of Ni-Ge-P deposition rate and Ge content as a function of aspartic acid and Ge(IV) concentration, respectively. A relatively low P content, ca. 1-2 at%, was observed in the case of films exhibiting a high concentration of Ge (> 18 at%). Like other members of its class, which includes molybdate and tungstate, Ge(IY) behaves a soft base according to the hard and soft acids and bases theory (HSAB) originated by Pearson [113, 114], capable of strong adsorption, or displaying inhibitor-like behavior, on soft acid metal surfaces. In weakly acidic solution, uncomplexed Ge(IV) most probably exists as the hydrated oxide, or Ge(OH)4, which, due to acid-base reactions, may be more accurately represented as [Gc(OH)4 nO ] ".

The phosphoramidite ligands that are the focus of the remainder of this chapter have prompted the investigation of ligands containing related structures. Iridium complexes of aspartic acid-derived P-chirogenic diaminophosphine oxides (DlAPHOXs) catalyze the amination [62] and alkylation [63] of aUyhc carbonates (Scheme 6). With BSA as base and catalytic amounts of NaPFs as additive, branched amination and alkylation products were obtained from cinnamyl carbonates in excellent yields and enantioselectivities. However, the yields and enantios-electivities were lower for the reactions of alkyl-substituted aUyhc carbonates. Added LiOAc increased the enantioselectivities of aUyhc alkylation products. 

An excellent review on protein hydrolysis for amino acid composition analysis has been published by Eountoulakis and Lahm [190], Hydrolysis can be performed by either chemical (under either acidic or basic conditions) or enzymatic means. The acidic hydrolysis itself can be carried out in a liquid or a gas-phase mode. The conventional acid hydrolysis uses 6M HCl for 20-24 h at 110°C under vacuum [200], In these conditions, asparagine and glutamine are completely hydrolyzed to aspartic acid and glutamic acid, respectively. Tryptophan is completely destroyed (particularly in the presence of high concentrations of carbohydrate), while cysteine and sometimes methionine are partially oxidized. Tyrosine, serine, and threonine are partially destroyed or hydrolyzed and correction factors have to be applied for precise quantification [190,201],... 

ATP, adenosine 5 -triphosphate BH4, 5,6,7,8-tetrahydrobiopterin BMPO, 5- er -butoxycarbonyl-5-pyrroline A-oxide DBNBS, 3,5-dibromo-4-nitrosoben-zene sulfonate DEPMPO, 5-diethoxyphosphoryl-5-methyl-l-pyrroline A-ox-ide DMPO, 5,5-dimethyl- 1-pyrroline A-oxide EMPO, 5-ethoxycarbonyl-5-methyl-l-pyrroline A-oxide GSH, glutathione (y-L-glutamyl-L-cysteinyl-glycine) HRP, horseradish peroxidase MNP, 2-methyl-2-nitrosopropane MPO, myeloperoxidase NAD(P)H, fl-nicotinamine adenine dinucleotide (3 -phosphate), reduced from NMDA, A-methyl-D-aspartic acid PBN, N-tert-butyl-a-phenylnitrone PMN, polymorphonuclear lymphocyte POBN, a-(4-pyridyl-l-oxide)-A-fer -butylnitrone SOD, superoxide dismutase TEMP,... 

Malate is oxidized to oxaloacetate by malate dehydrogenase (Figure 9.7). This reaction produces the third and final NADH of the cycle. [Note Oxaloacetate is also produced by the transamination of the amino acid, aspartic acid.]... 

The perhydroxy radical formed on the y-carbon atom (Reactions 30 and 31) is a likely precursor of aspartic acid, which we have found in yields of G = 1.1 when PGA was irradiated in 0.1% solution in 02. Further oxidation and a decarboxylation step would be required to give aspartic acid. However, it is not yet known whether the aspartic acid is formed solely as a result of irradiation it may be formed from a labile precursor during acid hydrolysis of the polymer. Our results differ from those reported by Friedberg and Hayden, who found high yields of aspartic acid in PGA irradiated in the absence of 02 we found only traces of aspartic acid from solutions of PGA irradiated under N2 (Figure 3). Glycine formation was not affected by the presence of 02. 

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