Define and describe the structure of proteins, including the forces that determi

The three-dimensional structure of a protein that is often key to its enzyme function. The structure of a protein is characterized in four ways:

Primary structure -  
-sequence of amino acids in a polypeptide chain, linked through peptide bonds.
-primary structure determines the three-dimensional structure of the protein and its property.

Secondary structure
local 3-D structure of the back bone of polypeptide.
Folding patterns in the  polypeptide backbone are stabilized by hydrogen bonds
(eg; alpa-helices, beta-sheets)

Tertiary structure -
-Three-dimensional arrangement of all atoms in the protein
-Dictated by primary structure
-Forces that stabilize tertiary structures are Hydrophobic Interactions, Electrostatic Interactions (salt bridges), Hydrogen bonds, Covalent Bond and Hydration

Quaternary structure- Is the arrangement of multiple folded protein or coiling protein molecules in a multi-subunit complex. Eg hemoglobin (it is a Tetramer of two ?-chains and two ?-chains)