Amino acids, peptides and proteins

Amino acids, peptides and proteins

Amino Acids

  • Amino acids are organic molecules comprised of a basic amine group (-NH2) a carboxylic acid group (-COOH) and an R group.
  • The R group is different in each amino acid and determines its properties.
  • There are 20 standard amino acids that are encoded by our genetic material to form proteins.
  • Every amino acid has a central carbon atom to which the amine group, carboxylic acid group, a hydrogen atom, and R group (or side chain) are bonded.

Peptides

  • Peptides are short chains of amino acids linked together through peptide bonds.
  • A peptide bond is formed by a condensation reaction between the carboxyl group of one amino acid and the amino group of another. A molecule of water is eliminated in this process.
  • Peptides have fewer than 50 amino acids. Longer chains are categorized as proteins.
  • Peptides, like all proteins, are linear polymers.

Proteins

  • Proteins are long chains of amino acids that have more than 50 amino acids. They are large, complex molecules.
  • Proteins are fundamental components of all living cells and include many substances, such as enzymes, hormones, and antibodies, that are necessary for the proper functioning of an organism.
  • They perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another.
  • Proteins are made from one or more polypeptides precisely twisted, folded, and coiled into a unique shape.
  • The structure of a protein is determined by its amino acid sequence. This structure, in turn, determines the protein’s function.
  • Proteins undergo a four-level structural organization: primary, secondary, tertiary, and quaternary. The primary structure is the linear sequence of amino acids, secondary structure involves alpha helices and beta sheets, tertiary structure consists of the three-dimensional folding of the protein, and quaternary structure involves the assembly of multiple protein molecules.