2 - Enzymes and Bioenergetics Flashcards
(25 cards)
Protein catalysts that increase the velocity of a chemical reaction and are not consumed during the reaction they catalyze
Enzymes
Physically distinct versions of a given enzyme, each of which catalyzes the same reaction
Isozymes
Catalyzes oxidations and reductions
Oxireductases
Catalyze transfer of moietes such as glycosyl, methyl or phosphoryl groups
Transferases
Catalyzes hydrolytic cleavage of C-C, C-O, C-N and other bonds
Hydrolases
Catalyze cleavage of C-C, C-O, C-N, and other bonds by atom elimination, leaving double bonds
Lysases
Catalyze geometric or structural changes within a molecule
Isomerases
Catalyze the joining together of two molecules coupled to the hydrolysis of ATP
Ligases
Bind in a transient, dissociable manner either to the enzyme or to a substrate
Cofactor
Serve as recyclable shuttles or group transfer agents
Coenzymes
Refers to enzyme only
APOenzyme
Refers to enzyme + cofactor
HOLOenzyme
Substrate concentration at which the reaction velocity is equal to 1/2 Vmax
Michaelis constant
Maximal velocity of an enzyme-catalyzed reaction
Vmax
The structure of the inhibitor resembles the substrate
Competitive inhibition
The inhibitor and the substrate bind at different sites of the enzyme
Noncompetitive inhibition
Increased Km
Competitive
Affinity of the enzyme to the substrate is decreased
Competitive
Vmax does not change
Competitive
Km does not change
Noncompetitive
Affinity of enzyme to the substrate does not change
Noncompetitive
Vmax is lowered
Noncompetitive
This equation describes how reaction velocity varies with substrate concentration
Michaelis-Menten Equation
Enzymes that follow Michaelis-Menten kinetics have a
Hyperbolic curve
