A Amino butyric acid

Purdy, RH, Morrow, AL, Moore, PHJ and Paul, SM (1991) Stress-induced elevations of a amino butyric acid type A receptor-active steroids in the rat brain. Proc. Natl. Acad. Sci. USA 88 4553 557. 

On the other hand, several examples of chiral sulfonamides derived from ehiral a-amino acids have been successfully employed as ligands for enantio-seleetive Diels-Alder reactions. Thus, Yamamoto and Takasu have easily prepared new chiral Lewis acids from borane and sulfonamides of various ehiral a-amino acids, which were further studied for their abilities to promote the enantioselective Diels-Alder reaction between methacrolein and 2,3-dime-thyl-1,3-butadiene. Since 2,4,6-triisopropylbenzenesulfonamide of a-amino-butyric acid gave the highest enantioseleetivity, this eatalyst was applied to the... 

The compounds investigated were the amino acids L-isoleucine, L-leucine, L-valine, and L-a-amino butyric acid. These compounds have similar molecular structures, as shown in Figure 2, and will be referred to throughout the present work as L-Ile, L-Leu, L-Val, and L-a-ABA. Where there is little likelihood of confusion, the designation L- will be omitted. Operations examined included crystallization of He through the addition of hydrochloric acid and through cooling. Under acidic conditions He crystallizes as a hydrochloride salt while in the vicinity of the isoelectric point (pH 5.2) it crystallizes as the neutral zwitterionic... 

Figure 2. Molecular Formulas of L-isoleucine, L-leucine, L-valine, and L-a-amino butyric acid...

Crystals Obtained by Acid Addition. Figure 4 shows the effect of initial solution composition on the impurity content of crystals obtained by acid addition. Clearly, this corresponds to the definition of an ideal system as presented above. These data show the order followed in impurity incorporation in the L-Ile crystals is L-Val > L-Leu > L-a-ABA, although there is only one data point on a-amino butyric acid. Also, the value of purification factors for all impurities is less than one. This means that purification by crystallization was indeed occurring. 

Fig. 5. Chromatogram of 24-hr urine specimen (sample 2/10 ml 360 ml/12 hr) in a case of hepatic coma in a 9-year-old child (D24). The following features are to be noted considerable increase in output of substances corresponding to all peaks presence of a-aminoadipic acid, a-amino-butyric acid (following the a-alanine peak), and tryptophan.

Alanine, a-amino- -butyric acid, and a-aminoisobutyric acid are prepared by permanganate oxidation of the N-benzoyl derivatives of the corresponding amino alcohols. The free amino acids are obtained from the benzoyl derivatives by hydrolysis with hydrochloric acid followed by treatment with aniline. Over-all yields for the four step process are 45-60%. 

The same approach was used to study the reductive modification of a methionine residue (Met ) in the amyloid-/ peptide [A/ (l-40)] and its reversed sequence [A/ (40-l)]. The A/3 peptide suffers the highly selective attack of H atoms on the Met residue, with the formation of a modified peptide containing an a-amino-butyric acid residue. Formation of tw -lipids in POPC system as a marker of radical damage to A/3 peptide clearly shows the transfer of radical damage from the peptide to the lipid domain. 

Alternatively, over very long time periods, L-amino acids can racemize to produce D-amino acids. However, measured d/l ratios for certain amino acids cannot be achieved based on known racemization rates of amino acids in seawater. For example, Lee and Bada (1977) calculated d/l ratios of 0.01 and 0.004 for aspartic acid and alanine, respectively, assuming an oceanic residence time of 3,400 years for these amino acids. These calculated values are much lower than the measured values and led Lee and Bada (1977) to conclude that the enhanced D-amino acid concentrations in marine DOM must be derived from a bacterial source. In a later paper, Bada et al. (1982) suggested that the near-racemic mixture (50% each of the d and l enantiomer) of alanine at depth in the ocean was a result of the dehydration of serine or threonine to produce racemic alanine. These authors also detected near racemic a-amino- -butyric acid (ABA), which can be produced from the dehydration of threonine. This mechanism of D-alanine formation... 

Figure 2. Chromatographic separation of amino acids after derivatization with phenylisothiocyanate (PITC) A. Separation of 200 picomole standard amino acid mix H containing 18 amino acids. B. Separation of an extended amino acid mix containing 28 amino acids. The standard one-letter abbreviations are used for the usual amino acids. Nonstandard amino acids are Sp, phosphoserine Hp, hydroxyproline Citr, citrulline Tau, taurine aAba, a-amino butyric acid HKl HK2, hyi oxylysines Om, ornithine , artifacts from reagents.

Due to an increased interest in analysis of physiological samples, we wanted to establish analyzer methods which would allow us to choose between our standard protocol for protein and peptide hydrolysates and a separate protocol for an expanded number of amino acids, to include the most important free amino acids found in physiological samples. A study of common analysis requirements in our facility indicated that only a limited number of the possible free physiological amino acids is needed for most unknown samples. These additional amino acids of interest are a-amino butyric acid, citrulline, y-amino butyric acid (GABA), hydroxyproline, hydroxylysine, ornithine, taurine, and tryptophan. Other amino acids of interest to us are phosphoserine, phosphothreonine, phosphotyrosine and carboxy-amino acids since they are released from glycoprotein or glycopeptide hydrolysates. 

In a similar manner the other amino acids react tyrosine, j3-p-hydroxy-phenyl-a-amino-butyric acid yielding p-hydroxy-phenyl-ethyl alcohol, tyrosol while phenyl-alanine, a-amino-j8-phenyl-propionic acid, yields phenyl-ethyl alcohol. Succinic acid, for example, which is of usual occurrence in fermented liquors is probably formed by a similar reaction from glutamic acid with the additional step of oxidation in the process. 

The N-acetyl-D,L-amino acid precursors are conveniently accessible through either acetylation of D,L-amino acids with acetyl chloride or acetic anhydride in a Schotten-Baumann reaction or via amidocarbonylation I801. For the acylase reaction, Co2+ as metal effector is added to yield an increased operational stability of the enzyme. The unconverted acetyl-D-methionine is racemized by acetic anhydride in alkali, and the racemic acetyl-D,L-methionine is reused. The racemization can also be carried out in a molten bath or by an acetyl amino acid racemase. Product recovery of L-methionine is achieved by crystallization, because L-methionine is much less soluble than the acetyl substrate. The production is carried out in a continuously operated stirred tank reactor. A polyamide ultrafiltration membrane with a cutoff of 10 kDa retains the enzyme, thus decoupling the residence times of catalyst and reactants. L-methionine is produced with an ee > 99.5 % and a yield of 80% with a capacity of > 3001 a-1. At Degussa, several proteinogenic and non-proteinogenic amino acids are produced in the same way e.g. L-alanine, L-phenylalanine, a-amino butyric acid, L-valine, l-norvaline and L-homophenylalanine. 

Production of L-isoleucine from ethanol and a-keto butyric acid or a-amino butyric acid using a multistep bioconversion with Brevibacterium flavum under native immobilization and biotin-free conditions (Mitsubishi Petrochemical Co., Inc.). Productivity of this system is 200 mmol 1-1 d "1. 

There is some question as to which internal standard should be employed. (Lindroth and Mopper, pers. comm., suggest a-amino butyric acid for seawater samples.)... 

Peak identification I = cysteic acid 2 = aspartic acid 3 = glutamic acid 4 = S-carboxy-methyl cysteine 5 = asparagine 6 = serine 7 = glutamine 8 = histidine 9 = threonine fO = glycine 21= arginine 22 = 3-alanine 23 = tyrosine 24 = alanine 25 =a-amino butyric acid 26 = tryptophan 27 = methionine 28 = valine 29 = phenylalanine 20 = ammonia 22 = isoleucine 22 = leucine 23 = ornithine 24 = lysine. Chromatograms courtesy of P. Lindroth and K. Mopper. 

The structure deduced from proton and carbon NMR, UV spectra, and comparison with the known 5-(j8-amino-/3-carboxyethyl)ergothioneine was further confirmed by chemical degradation in which treatment with Raney nickel gave L-threonine, L-a-amino- -butyric acid, and L-hercynine (Scheme 93). The l configuration of the amino acids was established by CD spectral comparisons with authentic samples. 

Isolation of ergobine, the [69] missing member of the series in the ergotamine group having a-amino-butyric acid as amino acid II... 

The lipophilic nature of one face of the molecule, created by the alkyl and phenyl moieties of the proline, (R)-a-amino butyric acid and the phenyl glycine residues respectively, is shown in Fig. 4. In contrast, the opposite face of the molecule, which presents five oxygen atoms and the dimethylamino function, is strongly hydrophilic (Fig. 5). 

Acetyl-a-amino- -butyric acid [34271-24-4] M 145.2, pK 3.72. Crystallise the acid twice from water... 

The existence of some amino acids (oxyglutamic acid, a-amino-butyric acid, norvaline, norleucine) claimed as protein constituents, could not be confirmed... 

Fig. 2. The elution pattern of a standard mixture of OPA-derivatized primary amines, separated on a 5 (Jim Nucleosil C-18 column (200 X 4.6 mm id). The flow-rate was 1 mL/min employing the indicated gradient of metlianol and Na phosphate buffer (50 mA4, pH 5.25). Each peak represents 39 pmol except for those indicated below. 1, glutathione 2, cysteic acid 3, O-phosphoserine (19.5 pmol) 4, cysteine sulfinic acid 5, aspartic acid 6, asparagine (19.5 pmol) 7, glutamic acid 8, histidine 9, serine 10, glutamine 11, 3-methyl-histidine 12, a-aminoadipic acid (9.8 pmol) 13, citrulline (9.8 pmol) 14, carnosine 15, threonine,glycine 16, O-phosphoethanolamine 17, taurine (19.5 pmol) 18, p-alanine (19.5 pmol) 19, tyrosine 20, alanine 21, a-aminoisobutyric acid 22, aminoisobutyric acid 23, y-amino-ii-butyric acid 24, p-amino-u-butyric acid 25, a-amino-butyric acid 26, histamine 27, cystathione (19.5 pmol) 28, methionine 29, valine 30, phenylalanine 31, isoleucine 32, leucine 33, 5-hydroxytryptamine (5-H i ) 34, lysine. The chromatographic system consisted of a Varian LC 5000 chromatograph and a Schoeffel FS 970 fluorimeter.

Among many L-amino acids tested, only L-valine and L-a-amino-butyric acid can replace L-alanine in MDP to give enhanced adjuvant active analogues (76). 

If it is not clear whether the reaction pH is correctly adjusted to around 11.5 by addition of the borate buffer, the use of an internal standard is recommended. Tlris especially holds true if hydrolysates are to be analysed. Although small amounts may be present in particulate matter, non-protein amino acids such as a-amino butyric acid or norleudne should be employed, the former having the advantage of being well separated in the HPLC system under discussion (Fig. 26-4). The internal standard should be added before the reagent. The amount added depends upon the type of analysis to be carried out and may vary from 25 to 500 pmol per injection volume. Variations in the response of the internal standard compared with a calibration run allow correction for differences in reaction pH, time and temperature. However, if these parameters have been kept constant for both calibration and sample analyses, the response should be reproducible to within about 2 %. 

Position 1 Alanine a-Amino butyric acid Valine... 

Bianchi, M.L., Crespi-Perellino, N., Giola, B. and Minghetti, A. (1982) Production by Claviceps purpurea of two new peptide ergot alkaloids belonging to a new series containing a-amino-butyric acid./. Nat. Prod., 45,191-196. 

In this way, a-ketobutyric acid formed from threonine can yield another amino acid, a-amino-butyric acid, via a transamination reaction. Reaction 1.51 is responsible for losses of hydroxy amino acids during protein hydrolysis. 

R = CH3 2-Amino crotonic acid (dehydro-a-amino butyric acid, Dhb )... 

Hydrogenolysis with Raney nickel of L-cystine and n-methionine respectively (Mozingo, Wolf, Harris and Fokera, 1943. Fonken and Mozingo, 1946) has confirmed the configuration assigned to natural cystine by Fischer and has also demonstrated that the methionine obtained from proteins is configurationally related to L(-h)a-amino-butyric acid. 

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