Methyl L-phenylalaninate

The vast majority of amino acid dehydrogenases use ammonium ions as the amine donor. However, recently a novel N-methyl-L-amino acid dehydrogenase (NMAADH), from Pseudomonas putida, was isolated and used to synthesize N-methyl-L-phenylalanine 36 from phenylpyruvic acid 31 and methylamine 35 in 98% yield and greater than 99%e.e. (Scheme 2.15). The enzyme was shown to accept a number of different ketoacids and also use various amine donors. Glucose dehydrogenase from Bacillus suhtilis was used to recycle the NADPH cofactor [17]. 

Enniatin A R = A/-methyl-L-isoleucine Enniatin B R = A/-methyl-L-valine Enniatin C R = A/-methyl-L-leucine Baeuvericin R = /V-methyl-L-phenylalanine... 

Fio. 6. Activities of the cyclopeptine synthetase complex (19). (1) Anthranilic acid ade-nylyltransferase (2) L-phenylalanine adenylyltransferase (3) covalent binding of anthranilic acid (4) covalent binding of L-phenylalanine (5) methylation of enzyme-bound L-phenylalanine by 5-ade-nosyl-L-methionine (6) translocation of AI-methyl-L-phenylalanine to enzyme bound anthranilic acid (7) release of cyclopeptine by cyclization. 

D-phenylalanine, iV-methyl-L-phenylalanine, A -methyl-L-/i-dimethyl-aminophenylalanine, 3-nitro-4-hydroxy-L-phenyIalanine y-methyl-L-proline, /3-methyl-L-proline D-serine... 

Mit Aralkyl- und Heteroaralkyl-halogeniden werden Ausbeuten von 80-94% und eine asymmetrische Induktion von meist 95% d.e. erreicht. Mit Alkyl-halogeniden betragt diese nur 17-35% d.e. Durch energische saure oder vorzugsweise alkalische Hydrolyse werden die freien (Sy-a-Amino-a-methyl-carbonsauren erhalten (z.B. a-Methyl-L-phenylalanin zu 67%)114-115. 

Hass, C.A7.. Neurath. H. Affinity labeling of bovine carboxypeptidase AgLeu by V-bromoacetyl-V-methyl-L-phenylalanine. II. Biochemistry 1971. 10. 3541-3546. 

With alcohols in the presence of dicyclohexylcarbodiimide, l-/f-benzotriazol-l-ol and a base [e.g. 4-(Me2N)CgH4N or Et3N] in bromobenzene, the corresponding esters were obtained. Similarly peptides with methyl glycinate and methyl-L-phenylalaninate were obtained by using the corresponding amino acid esters. [Isaacs Diederich Helv Chim Acta 76 2454 1993, Diederich et al. Chem Soc Rev 23 243 1994.]... 

Set-Up and Reaction Place 0.63 g of methyl L-phenylalaninate hydrochloride in a 50-mL Erlenmeyer flask. Add 10 ml of dimethylformamide and 0.3 ml of A/-methylmorpholine to the flask, swirl the flask to mix the contents, and place the flask in an ice-water bath. Label the flask as Solution A. 

Consider the spectral data for methyl L-phenylalaninate hydrochloride (Figs. 24.9 and 24.10). 

Discuss the differences observed in the IR and NMR spectra of L-phenylala-nine and methyl L-phenylalaninate hydrochloride that are consistent with the formation of the latter in this procedure. 

N-Bromoacetyl-N-methyl-h-phenylalanine. This is prepared by acyl-ating iV-methyl-L-phenylalanine with bromoacetyl bromide in alkaline solution. The product is crystallized from ethanol-water m.p. 109°. 

The mixture of amino acids released by complete hydrolysis of lipopeptin A was fractionated by ion-exchange chromatography. Each amino acid was isolated and the optical rotation determined. Two moles of L-aspartic acid and 1 mole each of L-glutamic acid, L-serine, l-threonine, N-methyl-L-phenylalanine, L-threo-p-hydroxyglutamic acid and N-methyl-L-aspartic acid were obtained. 

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