Aspartame, an artificial sweetener, is a peptide and has the following structure
`{:(" "CH_(2)C_(6)H_(5)),(" |"),(H_(2)N-CH-CONH-CH-COOCH_(3)),(" |"),(" "CH_(2)-COOH):}`
(i) Identify the four functional groups
(ii) write the Zwitter ionic structure
(iii) Write the structures of the amino acids obtained from the hydrolysis of aspartame
(iv) Which of the two amino acids is more hydrophobic ?

Answer

N/a

Explanation

`N_(2)N-underset(CH_(2)-COOH)underset(|" ")(CH" ")-CONH-overset(CH_(2)-C_(6)H_(5))overset(|" ")(CH" ")-COOCH_(3)`
(a) Functional groups :
(i) -COOH (carboxylic acid)
(ii) `-NH_(2)` (amino group)
(iii) -CONH (amide group)
`-COOCH_(3)` (ester)
(b) Zwitter ionic structure is :
`H_(3)overset(o+)N-underset(CH_(2)-COO^(Theta)" ")underset(|" ")(CH-CONH)-overset(CH_(2)-C_(6)H_(5)" ")overset(|" ")(CH-COOCH_(3))`
(c ) `H_(2)N-underset(CH_(2)-COOH)underset(|" ")(CH" ")-CONH-overset(" "CH_(2)-C_(6)H_(5))overset(|" ")(CH)-COOH_(3)overset("Hydrolysis")to`
`H_(2)N-underset((A)"Aspartic acid")underset(CH_(2)COOH)underset(|" ")(CH-)COOH+H_(2)underset((B)"Phenyl alamine")(N-CH-)overset(" "CH_(2)-C_(6)H_(5))overset(|" ")(CH-)COOH`
(d) Structure (B) is more hydrophobic in nature due to the presence of bulky phenyl group.