11589 17 Aspartame is used as a sweetener in many food products. It is a methyl ester of the dipeptide produced in the condensation reaction between aspartic acid and phenylalanine. O C N H C O CH CH2 OCH3 CH CH2 C O HO H2N Aspartame (a) Use the structure of aspartame to suggest structures for aspartic acid and phenylalanine. aspartic acid phenylalanine [2] 11589 [Turn over (b) Another amino acid derivative that is used as a food additive is monosodium glutamate which can be synthesised from glutamic acid. O O NH2 HO ONa monosodium glutamate (i) Circle on the structure above any chiral centre present in monosodium glutamate. [1] (ii) Draw the structure of the zwitterion formed by glutamic acid. [1] (iii) Write an equation for the reaction of glutamic acid with sodium carbonate to form monosodium glutamate. [2]