Proteins exhibit two secondary structures, a-helix, and b-pleated sheet, resulting from hydrogen bonding between >C=O and –NH– groups in the peptide bond. The a-helix forms a right-handed screw, while the b-pleated sheet resembles pleated folds of drapery.

The primary structure of proteins refers to the specific sequence of amino acids in a polypeptide chain. Any alteration in this sequence creates a distinct protein, making the primary structure crucial for protein identity.

Protein structure can be studied at four levels: primary, secondary, tertiary, and quaternary. Each level represents increasing complexity, with primary being the simplest and quaternary being the most complex.

Globular proteins have a spherical shape formed as polypeptide chains coil around. They are generally soluble in water. Examples of globular proteins include insulin and albumins.

Fibrous proteins have a fiber-like structure with parallel polypeptide chains held together by hydrogen and disulphide bonds. Examples include keratin (in hair, wool, silk) and myosin (in muscles).

A protein is a polypeptide with more than a hundred amino acid residues, having a molecular mass higher than 10,000u. However, the distinction is not sharp, and polypeptides with fewer amino acids might be called proteins if they exhibit a ...

Dipeptide is a product of the combination of two amino acids through a peptide bond. Similarly, tripeptide, tetrapeptide, and polypeptide are formed by the linkage of three, four, and more than ten amino acids, respectively, through peptide linkages.

A peptide bond, also known as a peptide linkage, is an amide formed between the -COOH group and -NH₂ group of amino acids. It is created through a reaction between the amino group of one amino acid and the carboxyl ...

Amino acids exhibit amphoteric behavior in aqueous solution due to the presence of both acidic (carboxyl group) and basic (amino group) groups, forming a dipolar ion or zwitterion. Naturally occurring a-amino acids, except glycine, are optically active due to the ...

Amino acids synthesizable in the body are termed non-essential, while those that cannot be synthesized and must be obtained from the diet are termed essential.