Bke2 Biochemistry Lectures

Amino acids, peptides & proteins
Reading material: Horton, Chapter 3, 4 (Stryer, Chapter 2).

Abstract: Proteins are built up from amino acids which are linked by peptide bonds to form a polypeptide of defined sequence. Many proteins are folded into well defined globular shapes because the hydrophobic effect forces hydrophobic side chains along the polypeptide sequence to cluster together in a hydrophobic core. The folded protein is stabilised by a large number of weak interactions. There are 4 levels of organisation, or structure, to a protein, going from the primary (1°) structure (the amino acid sequence), via secondary (2°) structure, tertiary (3°, 3D) structure, to quaternary (4°) structure in the case of multi-chain proteins. The amino acid side chains have a variety of chemical groups that make them particularly suitable for carrying out the numerous tasks they perform in the cells. In addition to the naturally occurring 20 amino acids, the repertoire is extended further by post-translationaly modified side chains.

Key concepts:
4°, 3°, 2°, 1° structure
Subunit
General amino acid structure
Types of amino acid residues (polar, hydrophobic, charged etc)
Peptide bond
Rigid and polar peptide unit
Polypeptide
Primary structure, N-terminus, C-terminus
Main chain
Side chain
Modified amino acids

Links:
Check out this excellent library of amino acids from the Molecular Models for Biochemistry at CMU site.

Here is a simple, one-page amino acid table summarizing basic information about the amino acids found in proteins.

Test your knowledge about amino acids by taking this interactive quiz.

Lecture index

[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35]