Proteins: Structure and Function Lecture

Proteins constitute 50% of the cellular dry weight, making them a major component of living organisms.

Jöns Jacob Berzelius, a Swedish chemist, coined the term 'proteins' for this vital class of organic compounds.

The term 'protein' originates from the Greek word 'proteios', which means 'first place'. This signifies the importance of proteins in living organisms.

Proteins are classified based on their structure and function, reflecting their diverse roles in biological processes.

Tertiary proteins are folded proteins with a single polypeptide chain, showcasing the intricate spatial arrangement of the chain.

Secondary proteins exhibit intra-hydrogen bonding within their structure, leading to specific shapes like alpha-helices and beta-sheets.

Quaternary proteins are complex structures formed by the association of multiple folded polypeptide subunits. This allows for even greater diversity in function.

Amino acids, the building blocks of proteins, contain two functional groups: amino group (-NH2) and carboxyl group (-COOH).

Hydroxyl group containing amino acids have an -OH group attached to their structure. This group plays a role in their chemical properties and interactions.

Aliphatic amino acids are classified into three types: mono amino mono carboxylic acid, mono amino dicarboxylic acid, and di/poly amino mono carboxylic acid.

Glycine, the simplest amino acid, belongs to the simple amino acid category. It has only a hydrogen atom as its side chain.

Heterocyclic amino acids contain cyclic structures within their side chains, such as tryptophan and histidine. These unique structures contribute to their diverse functions.

Regulatory or hormonal proteins are involved in intricate signaling pathways and control various biological processes, ensuring proper cellular function.

D-amino acids are the mirror image of L-amino acids, with an asymmetric and optically active alpha carbon atom. They are typically found in bacterial cell walls and some peptide antibiotics.

Contractile proteins, like myosin, actin, and tubulin, are crucial for muscle contraction and cell division, enabling movement and cell processes.

Amino acids can be classified based on their nutritional requirements. Essential amino acids cannot be synthesized by the body and must be obtained from the diet, while non-essential amino acids can be synthesized by the body.