ENZYMES
Dec 27, 2015
ENZYMESA type of Protein
MADE UP OF WHAT? A folded chain of amino acids
In living things they act asCatalysts
molecules that are used to speed up a chemical reaction without being changed in the reaction; the enzyme can be used over and over again
ENZYMESAre not SubstratesAre not ReactantsAre not Products
The participate in the reaction, but don’t change and can be reused (this is why they are “over the arrow”).
WHEN WE EAT ENZYMES…. We can’t use them…what has to happen first?
Eat enzymes??? If you eat anything that was, at one
point, a living cell or part of a living organism, you ARE eating enzymes!
ENZYMES (IN OUR BODIES)Break down enzymes (like any protein) in the digestive system.
Our enzymes are made by assembling these amino acids to form “human” proteins
Enzyme Activity Demo
ENZYMESAre needed for all chemical reactions includingDehydration synthesis and Hydrolysis
Provide the right “setting” for the chemical reaction
HOW DO ENZYMES WORK? Orient the substrate molecules correctly
Increase the likelihood a reaction will occur!
Enzyme Demo
ACTIVATION ENERGYEnzymes make it easier for substrates to reactThis is how the activation energy is
loweredActivation energy
The amount of energy needed to convert reactants into products
This is the “cost of the reaction”The enzyme is a “coupon”
ENERGY PLOT
Progress of the reaction
CHEMICAL REACTIONSSome chemical reactions release energyWhat has more energy, product or
reactants? What type of reaction is this?
Some reactions require energy inputAnswer the two questions above
again!
LABEL THE PARTS (ENZYME IS BLUE)
Active Site
Substrate (Reactant)
Products
Enzyme is unchanged
C A + B enzyme
SPECIFICITY OF ENZYMESEnzymes are EXTREMELY specific
There is a unique enzyme for EVERY substrate that reacts in the body
Each enzyme’s active site will ONLY fit one specific substrate
LOCK AND KEY MODEL
ACTIVE SITEpart of an enzyme where substrates bind and undergo a chemical reaction
If this location is changed (damaged, mutated, etc. , the reaction cannot take place.
WHAT IMPACTS ENZYMES Temperature
All enzymes have an optimal temperature.
Exceeding optimal may cause enzyme inactivation (denaturation) due to breakage of bonds in quaternary and tertiary structures.
WHAT IMPACTS ENZYMESpH
changing the concentration of H+ interferes with the bonds holding the protein in its folded shape.
Raising or lowering pH above or below optimal will cause denaturation.
OPTIMAL PHpH is?
changing the concentration of H+ interferes with the bonds holding the protein in its folded shape.
HOW FAST AN ENZYME WORKS ALSO DEPENDS ON:
Concentration of the Enzyme
Concentration of the Substrate (what it is putting together or taking apart).
COENZYMES AND COFACTORS
CoenzymesOrganic molecules such as vitamins
CofactorsInorganic molecules or ions such as Zn and
Cu Both attach to enzymes and improve chances that substrate will bind to the enzyme.
Cofactor animation
ENZYME INHIBITION Inhibit: shut down or suppress
Can be caused by outside molecule – drugs/poisons (poisons, drugs
Can be caused by inside molecule if your body wants to temporarily shut down a reaction
Why waste the energy?
EXAMPLES – EXTERNAL Cyanide inhibits one of the
enzymes in cellular respiration (oxidase)RESULT: less oxygen less ATP death
Penicillan works by inhibiting a bacterial enzyme involved in making the cell wall. The bacteria is unable to reproduce.
Nerve gas interferes with acetylcholinesterase
RESULT: acetylcholine cannot be hydrolyzed nerve signals cannot be passed from nerve cell to nerve cell.
EXAMPLE - INTERNAL Feedback inhibition in a biochemical pathways
Feedback inhibition uses the product concentration to stop “production”
COMPETITIVE INHIBITIONmolecules that are similar in shape
to the substrate bind to the active site and block the substrate; No chemical reaction can happen
Examples: Drugs and Insecticides
ANIMATION INHIBITION