Study Question: What are enzymes?

What are enzymes? Enzymes are proteins that increase the speed of chemical reactions. Enzymes are catalysts, which are substances that reduce the activation energy of a chemical reaction. Catalysts speed up chemical reactions!

Activation energy is the energy required to start a chemical reaction; enzymes reduce the activation energy of a reaction

Enzyme Active Site The active site of the enzyme is the area of the enzyme fits together with with the substrate (reactants).

Enzymes Are Proteins

Hair is structural protein, but NOT an enzyme

Proteins are made of amino acids

There are 20 Amino Acids

Amino Acids Amino Acids have a central carbon atom that is attached to the following: Hydrogen Amine Group Carboxyl Group R group- the functional group that differs between the 20 different amino acids

Amino Acids form Polypeptide Chains Peptide bonds are the bonds between amino acids in a polypeptide chain. When a peptide bond is formed in a condensation reaction, water is released.

The primary structure of a polypeptide chain refers to the sequence of amino acids. The sequence of amino acids is determined by the DNA.

Secondary Structure of Proteins After a polypeptide chain is formed, the protein may begin to fold or form a helix shape. Secondary structure is determined by hydrogen bonding. Beta pleated sheets (folding) and alpha helixes (spiral shape) are held by hydrogen bonds.

Tertiary Structure Bonds and interactions further effect the three-dimensional structure of a protein such as: Disulfide bridges Ionic Bonding Hydrophobic Interactions Hydrogen Bonding

Quaternary Structure One protein can be formed from multiple polypeptide chains.

Enzyme Structure and Function Enzymes have a very specific three dimensional structure. The structure of the enzyme determine the enzymes function. Enzymes are substrate specific. The substrate is the substance an enzyme acts on during a chemical reaction

What do Enzymes Do? Enzymes lower the activation energy of a biochemical reaction by holding the substrate in a way in which makes the reaction more likely to proceed. 

Enzymes can generally catalyze reactions in both directions amylase starch  glucose Starch  glucose Example: Amylase is an enzyme that can break down starch into glucose during digestion. Amylase may also catalyze a direction that bonds glucose molecules together forming a starch.

Enzyme Names Usually end in “-ase” Enzyme names commonly formed from the base name of the substrate it act on followed by “ase”. Examples Lipase is an enzyme that acts on lipids. Lactase is an enzyme that acts on lactose.

Enzymes can be denatured, meaning they can lose their shape

Enzymes may be inhibited by other compounds that bond to the active site.