Chapter 23, Problem 38A

Interpretation Introduction

Interpretation:

The two common shapes found in three dimensional folding of proteins should be described.

Concept introduction:

Proteins are polymeric biomolecules which are formed by the polymerisation of amino acids. Amino acids are the organic molecules with $–{\text{NH}}_{\text{2}}$ and −COOH functional groups bonded on same carbon atom of the molecule.

They polymerise by peptide linkage to form dipeptide, oligopeptide and polypeptide molecules. Each peptide bond formation is a condensation reaction that occurs with the elimination of water molecule.

Answer to Problem 38A

The two common shapes found in three dimensional folding of proteins is alpha helix and $\beta -\text{sheets}$.

Explanation of Solution

The polymeric biomolecules which are formed by the polymerization of amino acids are known as proteins. The three-dimensional geometry of a protein molecule is important to perform its function. There are four levels of structure which are used to describe the protein: Primary structure, Secondary structure, Tertiary structure and Quaternary structure.

The linear sequence of amino acids which forms the peptide chain denotes the primary structure.

Hydrogen bonding is present between different amino acids forms a three-dimensional geometry such as an alpha helix denotes the secondary structure. A spiral molecule is known as alpha helix.

The second major secondary structure is $\beta -\text{sheets}$. It composed of several beta strands which are linked laterally by hydrogen bonds result generally twisted pleated sheets looks like ribbon having regular peaks as a part of fabric.

Therefore, the two common shapes found in three dimensional folding of proteins is alpha helix and $\beta -\text{sheets}$.