Amino acids, peptides and proteins

This resource accompanies the Education in Chemistry article A meaty problem.

Learning objectives

1. Review the naming and structures of common amino acids.
2. Draw the structural formulas for dipeptides and tripeptides formed during protein synthesis and the component amino acids formed during hydrolysis.
3. Investigate how thin layer chromatography (TLC) can be used to separate amino acids in a mixture.
4. Calculate R_f values to identify individual amino acids.

Introduction

Alternatives to meat products, such as tofu and jackfruit, have been popular since the 1960s. Tofu is a product made from soybeans. More recently, food developers and technologists have used a naturally occurring protein, haem, to make plant-based meat alternatives look and taste more like actual meat. It is important for food scientists and technologists to understand the chemistry behind food processing.

The following tasks first guide you through the chemistry behind building protein molecules from their amino acid monomers in condensation reactions. The process of hydrolysis, which breaks peptide bonds within protein chains to reform amino acids, is then considered. Finally, the separation and identification of amino acids using R_f values in chromatography is investigated.

Reviewing understanding

Students successfully completing the questions will show understanding of the learning objectives:

• ‘Review the naming and structure of common amino acids’ is assessed using questions 1(a), 3 and 5 (b).  
• ‘Draw the structural formulas for dipeptides and tripeptides formed during protein synthesis’ is assessed using question 2. ‘Draw the structural formulas for… the component amino acids formed during hydrolysis’ is assessed using questions 3 and 5.
• ‘Investigate how thin layer chromatography (TLC) can be used to separate amino acids in a mixture’ is assessed using questions 4 and 5.
• ‘Calculate R_f values to identify individual amino acids’ is assessed using questions 4 and 5 (f).