Enzymology Flashcards
Turnover rate of an enzyme refers to
The fastest speed of an enzym
Enzymes work by reducing
Gibbs free energy of activation
Endergonic reactions are_________ and have a ________ G value
Non-spontaneous; positive
Exergonic reactions are__________ and have a _______G value
Spontaneous; negative
Enzymes do not change the overall Gibbs free energy change for the reaction OR the equilibrium concentrations of substrates and products. T/F
True
Hydrolysis of ATP is often used to drive other chemical reactions. T/F
True
What are the functions of proteases
To break down proteins
What is the function of the hexokinase enzyme
To transfer a phosphoryl group
The enzyme chymotrypsin is found where? What is its function
Small intestines
Digestive enzyme
The active site of chymotrypsin includes what amino acids?
Serine, histidine, and aspartic acid
Cofactors are proteins. T/F
False
Cofactors are of two types. What are they?
Coenzymes
Metal ions
Cofactors participate in catalysis by
Providing functional groups
In humans, cofactors are usually synthesized by
Vitamins
What reactions do oxide-reductases catalyze ?
Oxidation and reduction reactions
An example of an oxidoreductase is
Alcohol dehydrogenase
A common cofactor of alcohol dehydrogenase is
NAD+
What kind of reaction does transferases catalyze
Transfer of C-, N-, or P- containing groups
An example of a transferase is_______ and its function is_______
Glycerol kinase
To Transfer a phosphate group to glycerol to prepare it for glucose conversion during gluconeogenesis in the liver
What reactions do hydrolases catalyze?
Catalyze cleavage bonds by adding water
examples of a hydrolases include
Proteases, esterases, lipases,
What reactions do lyases catalyze ?
Catalyze cleavage of C-C, C-S, and some C-N bonds
What reactions do isomerases catalyze ?
Catalyze rearrangements of of isomers
What reactions do ligases catalyze
Formation of carbon and; O, S and N bonds
Essentially binding of 2 molecules
Competitive inhibitors bind to
The active site
Non-competitive inhibitors bind to
Anywhere other than the active site
Un-competitive inhibitors bind to
Anywhere other than the active site ONLY when the substrate is bound to the enzyme
What happens to Vmax and Km during competitive inhibition
Vmax remains the same, Km increases.
Small Km reflects _______ affinity of enzyme for the substrate
High
Large Km reflects________ affinity of the enzyme for the substrate
Low
For Lineweaver-Burk plots, the line representing competitive inhibition_________ on the y-axis with the uninhibited reaction
Intersect
What happens to Km and Vmax in no competitive inhibition
Km stays the same, Vmax decreases
What happens to Km and Vmax in uncompetitive inhibition
Both decrease
Suicide inhibition is when the inhibitor_________bonds to the enzyme and ________the concentration of the enzyme
Covalently; reduces
What happens to Km and Vmax in suicide inhibition
Vmax is decreased, Km stays the same
An example of suicide inhibition is
Penicillin
all enzymes follow Michaelis menten kinetics. T/F
False, allosteric enzymes do not
How many substrate binding sites do allosteric inhibitors have
At least 2
Allosteric activators ________ the Km and cause the enzyme to bind to substrate more readily
Decrease
Allosteric Inhibitors ________ the Km and cause the enzyme to bind less readily to substrate
Increase
Allosteric activators can only bind to the enzyme when the enzyme is in _____ configuration and inhibitors can only bind the enzym during_____ configuration
R; T
