Enzymes Flashcards
(28 cards)
What are the major six classes of enzymes?
LIL HOT Lipase Isomerase Lyase Hydrolase Oxidoreductase Transferase
Function of Oxidoreductases; and important info
catalyze oxidation-reduction reactions, often have a cofactor that acts like an electron transporter like NAD+ and NADP+.
The electron donor is known as the reductant
the electron acceptor is known as the oxidant
Function of Transferases; and important info
catalyze the movement of a functional group from one molecule to another. Kinases for example catalyze the transfer of a phosphate group like ATP to another molecule
Function of Hydrolases; and important info
catalyze the breaking of a compound into two molecules using water. phosphatase cleaves a phosphate group from another molecule
Function of Lyases; and important info
catalyze the cleavage of a single molecule into two products. do not require water. reversible function is referred to as a synthase
Function of Isomerases; and important info
catalyze the rearrangement of bonds within a molecule. can catalyze reactions between stereoisomers as well as constitutional isomers
Function of ligases; and important info
catalyze addition or synthesis reactions. generally between larger and similar molecules. often require ATP.
Thermodynamically enzymes work by?
lowering the transition state of reactions or lowering the activation energy
A very important characteristic of enzymes is that they do not alter the overall _ for a reaction, nor do that change the _ of a reaction
free energy
equilibrium
What is a substrate
a molecule which an enzyme acts on
What is an active site
the location within the enzyme where the substrate is held during the chemical reaction
What is lock and key theory
suggests that the enzymes active site (lock) is already in the appropriate conformation for the substrate (key)
What is the induced fit model
The substrate has induced a change in the shape of the enzyme
What are prosthetic groups
tightly bound cofactors that are necessary for enzyme function
What is the difference between apoenzymes and holoenzymes
apoenzymes= enzymes without cofactors holoenzymes= enzymes containing cofactors
Enzyme saturation refers to
once the reaction will no longer go any faster
The michaelis-Menten equation
v= vmax [S] / Km + [S}
When the reaction rate is equal to half of vmax Km =?
Km = [S]
What is the Hill’s coefficient
quantifies cooperativity of enzymes
If the Hill’s coefficient >1. what type of binding
positively cooperative binding is occurring, after one ligand is bound the affinity of the enzyme for further ligands increases
If the Hill’s coefficient <1. what type of binding
negatively cooperative binding is occurring, after one ligand is bound the affinity of the enzyme for further ligands decreases
If the Hill’s coefficient =1. what type of binding
the enzyme does not exhibit cooperative binding
optimum temperature for enzymes in the human body is
37C
optimal pH for enzymes in the human body is
7.4
