Revision: Biomolecules >> Vitamins Chemistry HSC Science (General) 12th Standard Board Exam Maharashtra State Board

α-Amino acids are carboxylic acids having an amino (–NH₂) group bonded to the α-carbon, that is, the carbon next to the carboxyl (–COOH) group.

The bond that connects α-amino acids to each other is called a peptide bond.

Chemically proteins are polyamides which are high molecular weight polymers of the monomer units, i.e., α-amino acids. OR It can also be defined as proteins are the biopolymers of a large number of α-amino acids and they are naturally occurring polymeric nitrogenous organic compounds containing 16% nitrogen and peptide linkages (-CO-NH-)

Enzymes are biological catalysts that speed up chemical reactions in living cells without being consumed in the process.

Bifunctional organic compounds containing a carboxylic and an amino group either at the same carbon atom or at nearby carbon atoms are called amino acids.

Chemically, proteins are polyamides, which are high molecular weight polymers of the monomer units called \[\alpha\]-amino acids.

• Origin of the name: The word "protein" is derived from the Greek word 'proteios', meaning "primary" or "of prime importance", reflecting proteins' essential role in living organisms.
• Chemical nature: Proteins are polyamides — high molecular weight polymers made up of monomer units called α-amino acids (general formula: RCH(NH₂)COOH).
• Nutritional sources: Key dietary sources of protein include milk, pulses, nuts, fish, and meat.
• Fibrous proteins have thread-like structures where polypeptide chains run parallel, held by hydrogen and disulphide bonds; they are insoluble in water — e.g., Keratin (hair, skin, nails) and Myosin (muscles).
• Globular proteins have a spherical shape where polypeptide chains coil around; they are soluble in water — e.g., Insulin, Egg albumin, and Legumelin.