Protein Structures

They are macromolecules formed by amino acids joined by peptide bonds.

 

They are present in all living beings and perform structural, catalytic, transport, defense, signaling and movement functions.

 

Its structure is organized into four levels:

 

1.-Primary structure

 

-Linear sequence of amino acids.

 

-Determines the folding and function of the protein.

 

2.-Secondary structure

 

Regular folds in the chain:

 

α-helix

 

β-pleated sheet

 

Stabilized by hydrogen bonds.

 

3.-Tertiary structure

 

-Complete three-dimensional shape of the protein.

 

-Determined by interactions between amino acid side chains.

 

Stabilized by ionic bonds, disulfide bonds, hydrophobic interactions and Van der Waals forces.

 

4.-Quaternary structure

 

Union of two or more polypeptide chains.

 

Example: Hemoglobin (has 4 subunits).