Enzyme Kinetics Flashcards
____ are protein that increase the rate of biochemical reactions
enzymes
Reactions could not occur without ____
enzymes
Enzymes make up ____ _____ such as ones that synthesize new molecules and generate cellular energy
metabolic pathways
what are the 3 main distinctive features of enzymes?
catalytic power, specificity, regulation
increasing the rate of biochemical reactions is what power of enzymes?
catalytic power
Selectively acting upon a substrate to carry out a particular reaction is what power of enzymes?
specificity
there are ______ of enzymes encoded in the human genome
1,000s
the ____ is the initial molecule in a reaction
substrate
Enzyme activity being regulated by a variety of mechanisms is what power of enzymes?
regulation
Enzymes ______ the free energy of activation of biochemical reactions
decrease
Enzymes ____ the rate of reactions
increase
Less ______ ___ _____ is needed for a reaction to occur when the temperature is high
gibbs free energy (activation energy)
The transition state is ______ for different temperatures
the same
At higher temps, ______ reactant molecules can be converted to products
more
more species cannot use temp to allow for reactions to occur because cells are _____ ______
temperature sensitive
How many categories of enzymes are there?
6
enzymes are _____ protein chains
globular
enzymes are classified based on their _______
activity
____ are enzymes that transfer electrons from one molecule to another
oxidoreductases
______ are enzymes that transfer chemical groups
transferases
Kinsases are a subgroup of what enzyme classification?
transferase
_____ add a phosphate group to proteins, carbs, lipids, and nucleic acids
kinases
_____ are enzymes that break covalent bonds by hydrolysis
hydrolases
proteases are a subgroup of what enzyme classification?
hydrolases
______ break down dietary protein by breaking peptide bonds
proteases
______ are enzymes that cleave various bonds or add groups to double bonds
lyases
_____ are enzymes that produce isomers
isomerases
_____ enzymes use up a water molecule each time they break a bond and add the H+ and OH- groups to the broken bond end
hydrolases
_____ are enzymes that join large molecules by forming covalent bonds
ligases
____ are enzymes used in DNA cloning to covalently link backbone strands of different DNA molecules to form intact strands
ligases
Do all enzymes need cofactors and coenzymes?
no
Cofactors or coenzymes are ___ or ___ _____ linked
covalently, non-covalently
_____ are metal ions or organic molecules that bind to enzymes and are required for enzyme activity
cofactors
heme, flavin, and c based molecules are examples of _____
cofactors
Coenzymes are a sub group of _____
cofactors
_____ are b vitamin organic molecule derivatives that act as enzyme cofactors
coenzymes
____ groups are tightly bound cofactors or coenzymes
prosthetic
______ are catalytically active complexes of protein and coenzyme
holoenzyme
____ are protein without the prosthetic group, and are not functional where a coenzyme is needed
apoenzyme
Velocity of reaction is another term for what?
rate of reaction
Velocity of reaction/rate of reaction is what?
amount of product formed or the amount of substrate consumed per unit time
v=k[A] is the equation for what?
first order reaction
In a ___ ____ _____, there is a directly proportionate relationship between substrate concentration and the amount of produce produced per unit time
first order relationship
v=k[A][B] is the equation for what?
second order reaction
In a second order reaction, _____ molecules reaction to form ____ products
2,2
What equation is used for the kinetics of enzyme catalyzed reactions?
Michaelis-Menton Equation
The M/M equation gives the rate of an enzyme reaction (v) in terms of what?
substrate concentration
What are the two constants in the M/M equation?
Vmax, Km
When substrate concentration is high, v= ____
Vmax
When substrate concentration is high, v is not longer dependent on what?
substrate concentration
When substrate concentration is high, the reaction is following what order kinetics?
zero
When substrate concentration is low, this is what order reaction?
first
v=(vmax/Km)*[S] is the equation when the substrate concentration is _____
low
What variables are fixed in the M/M equation?
temperature, pH, and ionic strength
___ ____ is the total concentration of the small ions
ionic strength
What is the shape of the curve of the M/M equation data?
hyperbolic curve
A ___ _____ is a curve that approaches but never reaches the max value
hyperbolic curve
v= ____/______
product produced/unit time
At Vmax/2, what is equal to what?
substrate, enzyme
Km is a measure of what?
amount of substrate/unit volume
Kcat is the value for what?
catalytic constant/turnover number
Kcat measures the _____ amount of product produced per second when the enzyme is ____ with substrate
maximum, saturated
What is the pH that most enzymes have peak activity?
7.4
Kcat must be determined and compared under what type of conditions?
the same
Kcat is similar to what other value?
Vmax
What temp do most enzymes peak activity at?
40C
kcat depends on what two things?
enzyme nature/efficiency, size/complexity of substrate
Staphylococcal nuclease has a _____ kcat
low (95)
Carbonic anhydrase has a ____ kcat
high (1,000,000)
What does enzyme staphylococcal nuclease do?
attack DNA,RNA, and other molecules
Why does carbonic anhydrase have such a high kcat?
CO2 and H2O are simple and small molecules
There is no activity at too low or too high of a pH because of the interactions of what part of the amino acid?
positively or negatively charged side chains
_____in an enzyme that breaks down food in the stomach, and is therefore at peak activity at a low pH of 1.5
pepsin
_____ in an enzyme that breaks down food in the intestines’ and has peak activity at pH 7.7
trypsin
What in the stomach makes it acidic?
HCl
At low temps, enzyme activity is ____ due to lack of energy
slowed
At high temps, enzymes might undergo irreversible ______
denaturing (unfolding)
denaturing of enzymes causes lack of ____
activity
