Quaternary structure of the Protein
FOUR ORDERS OF PROTEIN STRUCTURE:The modular nature of protein synthesis and folding are embodied in the concept of orders of protein structure: Primary structure--the sequence of amino acids in a polypeptide chainSecondary structure--the folding of sho (3-30 residue), contiguous segments of the polypeptide into geometrically ordered unitsTeiary structure--the assembly of secondary structural units into larger functional units such as the mature polypeptide and its component domainsQuaternary structure--the number and types of polypeptide units of oligomeric proteins and their spatial arrangementRef: Harper&;s Biochemistry; 30th edition; Chapter 5; Proteins: Higher Orders of Structure