Acetyl Alanine

IK Roterman, MH Lambert, KD Gibson, HA Scheraga. A comparison of the CHARMM, AMBER and ECEPP potentials for peptides. II. PHI-PSI maps for N-acetyl alanine N -methyl amide Comparisons, contrasts and simple experimental tests. J Biomol Stiaict Dyn 7 421-453, 198. 

A variety of radical products is observed following gamma radiolysis of the N-acetyl amino acids at 77 K (6), depending on the nature of the side chain of the parent amino acid. In the case of N-acetyl alanine, for example, the intermediates are (i) the anion radical IV (ii) the decarboxylation radical V (iii) the deamination radical VI and (iv) the alpha carbon radical VII. 

N 103 "A Comparison of the CHARMM, AMBER, and ECEPP Potentials for Peptides. II Acetyl Alanine IV-Methyl Amide ... 

Azidoocetyl-dl-olonine. See under Acetylal-anine and Derivatives, p A54 Azidoocetyl-dl-alonine Chloride. See under Acetyl alanine and Derivatives, p A54 Azidoocetyl Chloride. See under Acetyl Chloride and Derivatives, p A57... 

The t7 -correlation for carbonylic compounds suggested by Hart et al. (1967) can be applied to additional compounds thus, 2-pyrrolidone ( =l-3xl07 m—1 sec-1) (Szutka et al., 1965), asparagine in alkaline solution ( = 2-4x 107), acetylglycine and acetyl-alanine at pH = 9 (k 107 M-1 sec-1) (Braams, 1966) react at a rate practically equal to that of acetamide (k = 1-7 x 107 m-1 sec-1) (Hart et al., 1967). The ring closure seems to have little effect on the reactivity of the carbonylic group. 

The conformational angles derived in this study are unusual values in the Ramachandran map because these maps are based on conformational energy calculations for molecules as N-acetyl-alanine-N -methyl amide, which do not incorporate charged groups and thus will reproduce an uncharged peptide fragment better than an aqueous solution of a zwitterionic peptide. 

I. K. Roterman, M. H. Lambert, K. D. Gibson, and H. A. Scheraga,. Biomol, Struct. Dyn., 7, 421 (1989). A Comparison of the CHARMM, AMBER and ECEPP Potentials for Peptides. II. —d Maps for N-Acetyl Alanine N -Methyl Amide Comparisons, Contrasts and Simple Experimental Tests. 

Both enantiomers of A -acetyl alanine have a free carboxy group that can react with an amine in an acid-base reaction. If a chiral amine is used, such as (/ )-a-methyibenzyiamine, the two salts formed are diastereomers, not enantiomers. Diastereomers can be physically separated from each other, so the compound that converts enantiomers into diastereomers is called a resolving agent. Either enantiomer of the resolving agent can be used. 

Step [1] is just an acid-base reaction in which the racemic mixture of A -acetyl alanines reacts with the same enantiomer of the resolving agent, in this case (7 )-methylbenzylamine. The salts that form are diastereomers, not enantiomers, because they have the same configuration about one stereogenic center, but the opposite configuration about the other stereogenic center. 

To illustrate this strategy, we begin again with the two enantiomers of Ai-acetyl alanine, which were prepared by treating a racemic mixture of R)- and (S)-alanine with acetic anhydride (Section 28.3A). Enzymes called acylases hydrolyze amide bonds, such as those found in Ai-acetyl alanine, but only for amides of L-amino acids. Thus, when a racemic mixture of Ai-acetyl alanines is treated with an acylase, only the amide of L-alanine (the S stereoisomer) is hydrolyzed to generate L-alanine, whereas the amide of D-alanine (the R stereoisomer) is untouched. The reaction mixture now consists of one amino acid and one Ai-acetyl amino acid. Because they have different functional groups with different physical properties, they can be physically separated. 

There are increasing numbers of violations of these rules A-acetyl alanine, for example, being likely to be abbreviated Ac—Ala in the research literature or its correct abbreviation Ac—Ala—OH (but never Ac—A). This does not usually lead to ambiguity on the basis of the rule that peptide structures are written with the N-terminus to the left and the C-terminus to the right. Thus, Ac—Ala should still be correctly interpreted by a reader to mean CH3—CO—NH—CH(CH3)—C02H when this rule is kept in mind, since Ala—OAc (more correctly, H—Ala—OAc) would represent the mixed anhydride NH2—CH(CH3)—CO—0—CO—CH3 (there is a footnote about the term mixed anhydride on p. 152). 

In the asymmetric hydrogenation of acetamidoacrylate in water with this cationic (HO)4-BASPHOS catalyst (S)-N-acetyl alanine was obtained in quantitative yield and in more than 99% ee. Noteworthy is the unusually short time necessary in or-... 

L-specific carbamoylase from Pseudomonas putida IFO 12996 also hydrolyzes P-ureidopropionate 14, 36. The enzyme from Pseudomonas putida IFO 12996 was shown to be strictly L-selective and to be active on L-N-formyl- and also on L-N-acetyl-alanine 36. In this context it may be of interest that Runser and Meyer described a d-hydantoinase with no dihydropyrimidinase activity 37 and Ogawa et al. reported on the occurrence of a D-N-carbamoylase with no relation to a D-hydantoinase 38. ... 

Hydrogenation of methyl-2-acetamidoacrylate 2 with (R,R)-7z, at 1000/1 molar substrate/catalyst (S/C) ratio was very fast and reactions were complete in less than 10 minutes giving (/ )-methyl //-acetyl alanine in > 99 % e.e. (3 bar H2 pressure, room temperature). Under the same conditions, (S,S)-6a, gave (5)-methyl Macetyl alanine in > 99 % e.e. Conpetition reactions were carried out in order to gain a measure of the relative productivity of the two catalysts. These experiments involved using an equimolar mixture of (5,5)-6a and (R,R)-7a in the same reaction. Since the precatalysts have opposite enantiomers of ligand, then the closer the overall productivity given by the NBD and COD precatalysts, the... 

Table 2 Selected results for the synthesis of iV-acetyl alanine in the presence of organic solvents or with immobilized artificial metaUoenzyme (on sepharose) [39] ...

Hydroxyoxazolidin-2-ones 55 result from the action of aryl isocyanates on the hydroxy ketones 54 (94JPR509). N-acetyl-alanine, valine or leucine and dimethylformamido/ phosphorus oxychloride yield the (formyl-methylene )oxazolidinones 56 (R = Me, i-Pr or... 

The methyl ester 25a was found to extract iV-acetyl alanine/phenylalanine carboxylates from aqueous solution into chloroform with l d selectivities o/10 l, while the lipophilic analogue 2Sb transported /V-acetyl phenylalanine through apolar solvent barriers in up to 70% e.e. - ... 

The data in table 11.3 indicates that the benzyl ester of the acetyl alanine is also retained to the greatest extent on amylose as well as cellulose. However, on derivatized amylose, the chiral selectivity is also the greatest for this alanine derivative. This is in direct contrast to the selectivity exhibited from the derivatized celluloses. The unsubstituted carbamate and the 4-Cl substituted carbamate give the greatest retention, indicating strong general polar interactivity, but virtually no chiral selectivity at all. The 3,5-dimethyl and 4-methyl substituted derivatives of amylose show the best chiral selectivity for the alanine derivatives... 

Lucas, B. Gregoire, G. Lemaire, J. Maitre, R Glotin, F. Scheimann, J.R Desfrancois, C. Infrared multiphoton dissociation spectroscopy of protonated N-acetyl-alanine and alanyl-histidine. Int. J. Mass Spectrom. 2005, 243, 105-113. 

C5H8N03]- CH3C0NHC(CH3)C00H Reaction of HO- with acetyl-alanine (Ti H202)/ HjO EPR/ 300 3H(i ,CH3) 1.81 70Tanl... 

Photolysis of acetyl alanine/ Polycrystalline EPR/ 300 2.00 3H(CH3) 1.9 68Johl/ 68Gaml, 64Johl... 

Line broadening by hindered rotation. Corresponding radicals from acetylglycylleucine and acetylglycylcinemethylester also observed. ) Line broadening by hindered rotation. Corresponding radicals from acetyl-alanine and -valine also observed. 

Synonyms Apron 2E CGA 117 CGA 48988 A-(2,6-Dimethylphenyl)-7V-methoxy-acetyl)alanine methyl ester A-(2,6-Dimethylphenyl)-A-methoxyacetyl)-DL-alanine methyl ester Metalaxil Methyl A-(2,6-dimethylphenyl)-A -(methoxyacetyl)-DL-alaninate Ridomil Ridomil E Subdue Subdue 2E Subdue 5SR... 

Highly functionalized halides give generally positive results. p-Iodo N-acetyl-alanine methyl ester was used to introduce the amino acid residue into an olefinic protected sugar (Fig. 57),300... 

The two thionated A(-acetyl-alanine-A(-methylamides (83) and (84)138 more sophisticated A(-phenylthioacetyl con-... 

Figure 22 Structural representation of (a) the inteaction between guanidinopyrrole receptor 86 and acetyl-alanine and (b) the interaction between guanidinopyrrole tripeptide 87 and tetrapeptides.

The first example of a combination of a metal-catalyzed substrate synthesis with a biotransformation conducted in a one-pot maimer proceeding according to Scheme 19.23 was reported by Hanefeld, Maschmeyer, Sheldon, and coworkers in 2006 [58]. In this pioneering work, enantioselective hydrogenation of methyl N-acetyl amino acrylate (72) with a heterogenized rhodium-diphosphane complex as catalyst gave the N-acetyl alanine (S)-73 with 100% conversion and 95% ee. This intermediate was then directly converted in situ after separation of the immobilized metal catalyst by means of an L-amino acylase (Scheme 19.23). This enzymatic resolution then led to the formation of the desired amino acid L-alanine (l-74 (S)-74) with 98% conversion and with an excellent enantiomeric excess of >98%. 

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