Folding of protein chain is due to

In the concept of orders of protein structure: primary structure--the sequence of amino acids in a polypeptide chainsecondary structure--the folding of sho, contiguous segments of the polypeptide into geometrically ordered units teiary 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 arrangement.Two most common types of secondary structure, the a helix, and the b sheet.The stability of an a helix arises primarily from hydrogen bonds formed between the oxygen of the peptide bond carbonyl and the hydrogen atom of the peptide bond nitrogen of the fouh residue down the polypeptide chainLike the a helix, b sheets derive much of their stability from hydrogen bonds between the carbonyl oxygens and amide hydrogens of peptide bonds. However, in contrast to the a helix, these bonds are formed with adjacent segments of the b sheetRef: Harper&;s Biochemistry; 30th edition; Pg: 38