Proteins

Functions of ProteinsSome Functions of Proteins

Type of protein Example Function

Enzymesamylase Promotes the break down of starch to the simple sugar glucose.

Structural proteinskeratin, collagen Hair, wool, nails, horns, hoofs, tendons, cartilage

Hormonesinsulin, glucagon Regulates use of blood sugar

Contractile proteinsactin, myosin  Contracting fibers in muscle

Storage proteinsferritin Stores iron in spleen

Transport proteins

hemoglobinserum albumin

Carries oxygen in bloodCarries fatty acids in blood

Immunological proteinsantibodies Rid the body of foreign proteins

Toxinsneurotoxin Cobra venom blocker of nerve functions

• Proteins-macromolecules/polymer with amino acid monomers. Ex: enzymes (speed up reactions), insulin (hormone) and collagen (connective tissue)

• Amino acids-organic molecules possessing both carboxyl (COOH) and amino groups (NH3)

20 different types of amino acids

• Two amino acids bond together bycondensation synthesis form a dipeptide.

-the bond is called a peptide bond.

• Polypeptide-a single chain of amino acids.

Levels of Protein Organization

• Four Levels:1.) Primary Structure-polypeptide with a linear

sequence, in which amino acids are joined by peptide bonds

Can be made up of 20 different amino acids

2.) Secondary Structure-polypeptide takes on a particular orientation in space, in which peptide bonds and hydrogen bonds are present:

-Alpha helix–Beta pleated sheets.

3.) Tertiary Structure-polypeptide with a three dimensional shape connected by peptide, ionic, covalent, and hydrogen bonds all take place.

4.) Quaternary Structure- More than one chain of amino acids is present

• Denaturation-bonding that has been disrupted due to pH change or temperature

– Once a protein loses its shape, it is no longer able to perform its usual function.

– Can be permanent

• protein structures

…Denaturation in Nature…