Sweet tooth, but calorie conscious. Aspartame(NutraSweet),...

Name: Problem 9, Chapter 2: Biochemistry
Uploaded: 2020-07-29T19:25:44-08:00
Duration: 1 min 30 s
Channel: Jessica Honkomp
Description: Sweet tooth, but calorie conscious. Aspartame(NutraSweet), an artificial sweetener, is a dipeptide composed of Asp-Phe in which the carboxyl terminus is modified by the attachment of a methyl group. Draw the structure of Aspartame at pH 7.

Sweet tooth, but calorie conscious. Aspartame(NutraSweet), an artificial sweetener, is a dipeptide composed of Asp-Phe in which the carboxyl terminus is modified by the attachment of a methyl group. Draw the structure of Aspartame at pH 7.

Key Concepts

Amino Acid Ionization States at Physiological pH

At pH 7, amino acids and peptides exist in forms dictated by the ionization of their functional groups. The amino groups are generally protonated (–NH3+) and the carboxyl groups are deprotonated (–COO–), except when modified. Understanding these protonation states is key for drawing the correct structure of aspartame at physiological pH.

Peptide Bond Formation

A peptide bond is a covalent bond formed between the carboxyl group of one amino acid and the amino group of another, creating a dipeptide or larger polypeptide. In the context of aspartame, this bond connects the amino acids aspartic acid and phenylalanine, illustrating the basic principle of peptide synthesis.

Esterification (Methyl Ester Modification)

Esterification refers to the chemical reaction in which a carboxyl group reacts with an alcohol, resulting in the formation of an ester. In aspartame, the carboxyl terminus is modified by attachment of a methyl group, transforming the typical carboxylate group into a methyl ester, which affects the overall charge and reactivity of the molecule.

Structure of Dipeptides

A dipeptide is composed of two amino acids linked by a peptide bond. In aspartame, the structure is derived from aspartic acid at the N-terminus and phenylalanine at the C-terminus, with the additional methylation at the carboxyl group. This structural arrangement impacts the molecule’s properties, including its taste and metabolic behavior.

Transcript

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