Each year over 500 tons of protease enzymes are added to laundry detergents to break down proteins such as the pizza stains on your shirt. These enzymes are produced by bacteria grown in huge stainless steel tanks. ENZYMES. What are enzymes?
Each year over 500 tons of protease enzymes are added to laundry detergents to break down proteins such as the pizza stains on your shirt. These enzymes are produced by bacteria grown in huge stainless steel tanks.
What are enzymes?
- Biological molecules that catalyze, or speed up, chemical reactions in biological systems by lowering their activation energy
- Activation Energy Initiates Reactions: In any chemical reaction, an initial stable state must become less stable before change is possible
How enzymes work
- Enzymes Lower the Energy Barrier
- Although the activation energy is lower in an enzyme-catalyzed reaction than in an uncatalyzed reaction, the energy released is the same with or without catalysis. In other words, Ea is lower, but ΔG is unchanged.
- An enzyme is a protein catalyst with an active site capable of binding one or more substrate molecules, forcing them into the transition state
- Bring substrates in the correct position
(B) physical strain
- Make bonds weaker and easier to rearrange
(C) chemical charge
- add/remove ions to destabilize the substrate
3. Catalyzed Reactions Reach a Maximum Rate
- Because there is usually less enzyme than substrate present, the reaction rate levels off when the enzyme becomes saturated.
a) Enzymes can be activated my co-enzymes/ co-factors
b)Enzymes can be inhibited, by inhibitors
Ex. Irreversible Inhibition DIPF forms a stable covalent bond with the side chain of the amino acid serine at the active site of the enzyme trypsin, thus irreversibly disabling the enzyme.
Reversible Inhibition: A competitive inhibitor binds temporarily to the active site of an enzyme
A noncompetitive inhibitor: binds temporarily to the enzyme at a site away from the active site. In both instances, the enzyme’s function is disabled for only as long as the inhibitor remains bound.
Allostery and Reaction Rate How the rate of an enzyme-catalyzed reaction changes with increasing substrate concentration depends on whether the enzyme is allosterically regulated.
Feedback Inhibition of Metabolic Pathways The commitment step is catalyzed by an allosteric enzyme that can be inhibited by the end product of the pathway. The specific pathway shown here is the synthesis of isoleucine, an amino acid, from threonine in bacteria. This pathway is typical of many enzyme-catalyzed biological reactions.
pH Affects Enzyme Activity
- Each enzyme catalyzes its reaction at a maximum rate at a particular pH.Ex. pepsin is a protease active in the acidic environment of the stomach.
b)Temperature Affects Enzyme Activity
-Each enzyme is most active at a particular optimal temperature. At higher temperatures, denaturation reduces the enzyme’s activity.