Phenylalanine from aspartame hydrolysis

Perhaps the most successful and widely used artificial sweetener is aspartame, the methyl ester of a dipeptide formed from phenylalanine and aspartic acid. Aspartame is roughly 100 times as sweet as sucrose. It undergoes slow hydrolysis in solution, however, which limits its shelf life in products such as soft drinks. It also cannot be used for baking because it decomposes with heat. Furthermore, people with a genetic condition known as phenylketonuria cannot use aspartame because their metabolism causes a buildup of phenylpyruvic acid derived from aspartame. Accumulation of phenylpyruvic acid is harmful, especially to infants. Alitame, on the other hand, is a compound related to aspartame, but with improved properties. It is more... 

Metabolism. Aspartame is metabolised by the body into its two constituent amino acids and methanol. These hydrolysis products are handled by the body in the same way as the aspartic acid, L-phenylalanine and methanol from other commonly consumed foods. It adds nothing new to the diet. 

Aspartame. Aspartame is a widely used intense sweetener that has excellent taste characteristics, ft is a peptide made from two amino acids, phenylalanine and aspartic acid, but will in an acidic beverage medium slowly hydrolyse to its components. The fact that aspartame is a source of phenylalanine is of concern to consumers with certain complaints, and suitable label declarations are now required by law. Technically, this slow hydrolysis brings about loss of sweetness. 

Aspartame is a newer sweetener/flavor enhancer but it too may cause angiodema and urticaria. It is contraindicated in patients suffering from phenylke-tone urea, as hydrolysis can lead to formation of phenylalanine. 

The first protease-catalyzed reaction in ILs was the Z-aspartame synthesis (Scheme 10.7) from carbobenzoxy-L-aspartate and L-phenylalanine methyl ester catalyzed by thermolysin in [BMIM] [PF ] [ 14]. Subtilisin is a serine protease responsible for the conversion of A -acyl amino acid ester to the corresponding amino acid derivatives. Zhao et al. [90] have used subtilisin in water with 15% [EtPy][CF3COO] as cosolvent to hydrolytically convert a series of A -acyl amino acid esters often with higher enantioselectivity than with organic cosolvent like acetonitrile (Scheme 10.8, Table 10.2). They specifically achieved l-serine and L-4-chlorophenylalanine with an enantiomeric access (ee) of-90% and -35% product yield which was not possible with acetonitrile as a cosolvent [90]. Another example is hydrolysis of A-unprotected amino acid ester in the presence of a cysteine protease known as papain. Liu et al. 

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