What Is Protein

What is protein?

Proteins are large molecules that are composed of amino acid subunits. Amino acids consist of a central carbon atom that is bonded to an amino group, carboxyl group, Hydrogen atom and an R group. The R group can vary, but it is either an atom or a group of atoms. Proteins are polymers of amino acids, each bonded by peptide bonds.

The functions of proteins can vary. There are many types of proteins, such as: storage, structural, transport, and defensive proteins. Enzymes are also proteins.

There are four levels of a protein structure:

• Primary structure
  • Provides the order or sequence of the amino acids
• Secondary structure
  • A 3D shape produced by the hydrogen bonding between amino and carboxyl groups from adjacent amino acids.
    • Can be an alpha helix spiral shape or a beta pleated sheet.
• Tertiary structure
  • Another level of a 3D shape, often times forming a globular shape. The additional 3D shape produced during the tertiary structure is influenced by hydrogen bonding and ionic bonding between R groups, and even the formation of a disulfide bond.
• Quaternary structure
  • This is protein that that has two or more separate peptide chains

Example: hemoglobin

Quick Facts about Protein:
·  Proteins: large molecules that are composed of amino acid subunits

• There are 20 different amino acids

·  Functions of protein

• Protein can act as antibodies, carriers, channels, enzymes, receptors, and even structural components

·  The different levels of protein

• 1° structure
• The sequence of amino acids
• 2° structure
• Weak hydrogen bonds
• Can form two types of shapes
• Alpha helix
• Beta pleated sheet
• 3° structure
• Three dimensional shape formed by the polypeptide chains
• 4° structure
• Different polypeptide chains covalently bond

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