Phenylalanine has previously been resolved by fractional crystallization of the brucine salt of formyl-nn-phenylalanine (1) or of the cinchonine salt of benzoyl-nn-phenylalanine (2). Enzymatic methods have also been used for the resolution. According to the method of Gilbert, Price, and Greenstein (3), racemic phenylalanine is resolved by subjecting its Nchloroacetylated derivative to asymmetri...

Optical resolution of racemic 5-oxo-1-phenyl-pyrazolidine-3-carboxylic acid 2 with L-amino acid methyl ester via the diastereomers formation was investigated. Treatment of racemic 5-oxo-1-phenylpyrazolidine-3-carboxylic acid 2 with L-valine methyl ester gave diastereomers with a total yield of 86%. The diastereomeric dipeptides can be easily separated by flash column chromatography. Acidic clea...

1. The inhibition of pepsin-catalysed hydrolysis of N-acetyl-l-phenylalanyl-l-phenylalanylglycine by products and product analogues was studied. 2. The non-competitive nature of the inhibition by the product N-acetyl-l-phenylalanine confirms an ordered release of products, and points to a common mechanism (involving an amino-enzyme) for pepsin-catalysed transpeptidation and hydrolysis reactions...

L-Tyrosine and L-Dopa are the precursors in the biological synthesis of amine neurotransmitters. On the other hand, phenylalanine as an aromatic amino acid (AAA) is a precursor in the synthesis of L-Tyrosine and L-Dopa. For some substrates such as amino acids, resolution by the formation of diastereomers offers an attractive alternative. Among different methods in this case, crystallization-ind...

Dipeptide synthesis by aminopeptidase from Streptomyces septatus TH-2 (SSAP) was demonstrated using free amino acid as an acyl donor and aminoacyl methyl ester as an acyl acceptor in 98% methanol (MeOH). SSAP retained its activity after more than 100 h in 98% MeOH, and in the case of phenylalanyl-phenylalanine methyl ester synthesis, the enzyme reaction reached equilibrium when more than 50% of...

The reaction of furylacrylic acid with cyclopentadiene in toluene gave the expected Diels-Alder endo-and exo-adductsin -1 : 1 ratio. The adducts were separated by iodolactonization method to provide 3-endo-(2'-furyl) bicyclo 12.2.11 hept-5-ene- 2-exo-carboxylic acid and 3-exo-(2'-fury1)bicyclo 12.2.11 hept-5-ene-2-endocarboxylic acid. Esterification of these acids by MeI / HMPA gave the exp...

Aspartame (SC-18862, 3-amino-N-(a-carboxyphenethyl)succinarnic acid, methyl ester; the methyl ester of aspartyl-phenylalanine ) is a sweetening agent that organoleptically has about 180 times the sweetness of sugar. Because it so closely resembles naturally occurring dipeptides, it was believed that it would be digested in a similar manner. To show this, the metabolism of [14C]aspartame labeled...