ENZYMES

Definition of Enzymes: A globular protein which functions as a CATALYST. Enzyme Animation

Location of Enzymes Protein molecules are produced by living cells. Each cell contains several hundred different enzymes. They promote a vast number of rapid chemical reactions between a temperature limit suitable for the particular organism About 5-40oC Without these catalysts, we would have to heat up organisms to a point that is lethal or the reaction would be too slow to sustain life.

Enzyme is a Catalyst A catalyst is a substance that speeds up a chemical reaction without being used up in the reaction.

In Short Enzymes make reaction happen faster at lower temperatures Reactions that include thinking, breathing, heart beat, eating, walking…

Some helpful terminology: SUBSTRATE: The substance (reactants) that an enzyme acts on and makes more reactive. This could be another protein, lipid, carbo. or nucleic acid. Ex. Lactase (enzyme) that acts on lactose (substrate)

ACTIVE SITE: The area of an enzyme molecule which binds to the substrate. Groove in enzyme surface, formed with only a few of its amino acids. Draw the active site

“Lock and Key” Enzyme specificity is based on compatible fit between shape of active site and shape of substrate. The substrate is the key whose shape is complementary to the enzyme or lock.

“Lock and Key”…Specificity A different substrate would need a different “Lock” …enzyme! This is called SPECIFICITY!

Example Starch which is then broken down into maltose (a disaccharide) parts by the enzyme amylase. Amylase Starch  Maltose (amylase is the enzyme in saliva) To break maltose into glucose, a different enzyme is needed…maltase. Maltase Maltose  Glucose

Enzymes do not actually change in the reaction. They leave the reaction unaltered.

RATE OF REACTION: The time it takes to break down a given amount of substrate into a given amount of product. Example: The more enzyme present, the faster the substrate will be broken down.

POISONS: Mercury and Lead -these cause enzyme molecules to clump together so they become useless (inactive)

THE WHOLE ENZYME STRUCTURE: Most of it is made of protein. They also need a non-protein part to work

THE WHOLE ENZYME STRUCTURE: Non-Proteins such as minerals like Iron Magnesium Vitamins These are needed to make the correct attachment (active site) so that the enzyme can do its job. This is one of the reasons we need to have certain vitamins and minerals in our diet.

Denaturation: Loss of the 3-D shape of a protein (it unravels). This destroys the active site Caused by: Heat, Cold, Chemical agents, pH change (too acidic or basic) This is why a temp. of over 104° F is dangerous and person should go to the hospital.

Denaturation: causal agents Heat: Irreversible ex. Cooked egg Agitates the polypeptide chain enough to over power the weak interactions.

Help, Help I’m denaturing!!!!! Ohhh, the cold water is denaturing my enzymes and starting to destroy their 3D globular shape resulting in their loss of a proper active site. Help, Help I’m denaturing!!!!!