Proteins

• Amino acids are the building blocks of proteins
• Proteins: composed of Carbon, Hydrogen, Oxygen, Nitrogen, and Sulfur (C, H, O, N, S)
• Amino acids are the building blocks of proteins and have a general structure consisting of an amino group (NH2), a carboxyl group (COOH), and a side chain
• There are 20 naturally occurring amino acids, each with a unique side chain that differentiates them from one another
• The side chain of each amino acid is what differentiates one amino acid from another
• A dipeptide is formed when two amino acids join together by a peptide bond
• A polypeptide is formed by many amino acids joining together through condensation reaction
• Protein structure pt1

  Primary structure

  • It's the number and sequence of amino acids in the the polypeptide chain
  • Determines the structure of the polypeptide and the 3D shape of proteins and their active sites
  • Peptide bonds are involved
• Proteins have two main secondary structures:

  • Alpha helix: forms a right-handed coil stabilized by hydrogen bonds between amino acids. They make up DNA binding and transmembrane proteins
  • Beta pleated sheets: formed by proteins due to hydrogen bonds between amino acids, creating a sheet-like structure like silk
• The secondary structure of proteins form two shapes due to hydrogen bonds forming between amino acids
• Proteins' tertiary structure involves hydrogen bonds, ionic bonds, disulfide bonds, hydrophobic, and hydrophilic interactions
• The tertiary structure of a protein provides the final 3D shape necessary for its function
• Haemoglobin is an example of a protein with quaternary structure
• Quaternary structure is found in proteins that consist of more than one polypeptide chain
• Globular proteins:

  • Have water inside that pertains a spherical shape
  • Are soluble
  • Involved in metabolic processes because they have hydrophobic and hydrophilic R groups
  • Examples: Haemoglobin, Insulin, and Pepsin
  • The hydrophobic R groups are on the inside, while the hydrophilic ones are on the outside
• Give three examples of Globular proteins

  1. Haemoglobin

  2. Insulin

  3. Pepsin
• Examples of fibrous proteins include Collagen, Keratin, and Elastin
• Globular and fibrous proteins are two main types of protein structure
• Haemoglobin is a globular protein that carries oxygen in the blood
• Haemoglobin consists of four polypeptide chains: two alpha and two beta chains
• Each haemoglobin molecule contains a haem group with iron (Fe2+) that can bind to two oxygen molecules
• The haem group is a prosthetic group that is embedded in the globular protein structure of haemoglobin
• Fibrous protein

  • Usually made of long polypeptide chains that form fibres
  • Insoluble due to high number of amino acids with hydrophobic R-groups in their primary structure
  • Flexible