Proteins

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[2015 Syllabus updates are colour highlighted]

Proteins are sequences of amino acids joined by peptide links.

Hydrolysis of the peptide link produces the constituent amino acids.

Mixtures of amino acids can be separated and identified by thin-layer chromatography

The importance of hydrogen bonding and sulfur–sulfur bonds in proteins.

The primary, secondary (α-helix and β–pleated sheets) and tertiary structure of proteins.

Amino acids can be located on a chromatogram using developing agents such as ninhydrin or ultraviolet light and identified by their Rf values.

Students should be able to:

• draw the structure of a peptide formed from up to three amino acids

• draw the structure of the amino acids formed by hydrolysis of a peptide

• identify primary, secondary and tertiary structures in diagrams

• explain how these structures are maintained by hydrogen bonding and S–S bonds

• calculate Rf values from a chromatogram.