Unit 6 Flashcards
reactants/substrates are ___ the arrow
before
products are ___ the arrow
after
A+B –> C+D
A+B are the ____/____
reactants/substrates
A+B –> C+D
C+D are the ____
products
A+B –> [AB] –> C+D
[AB] is the ___
intermediate
the intermediate is not _____
isolatable
–> means that the reaction is ____
irreversible
means the reaction is ____
reversible
rate of a rxn is determined by 5 things
[reactants] temperature pH activation E and the energy barrier [products]
forward and reverse reactions occur ____, although the ____ reaction rates are different
simultaneously
initial
both forward and reverse reactions are happening at the ____ same time, but at ___ rates
same
different
____ _____: the concentration of the products cannot increase further
equilibrium state
at equilibrium states, the forward and reverse reactions are still happening, but with no ___ __
net change
2 formulas to calculate equilibrium constant Keq
[products]/[reactants]
k1(rate of forward reaction)/k-1(rate of backward reaction
___ ___: when two reactants collide A+B. energy is released
activation energy
activation energy must be ___ than energy barrier for the reaction to proceed
greater
activation energy can be demarcated by 2 things
Ea or (delta)G*
___ ___: the amount of energy required for the formation of products
energy barrier
+(delta)G
low energy state–>high energy state
costs energy
-(delta)G
high energy state–>low energy state
releases energy
____ ___/____: how fast the products are formed
reaction rate
velocity (v)
reaction rate/velocity: measured ____ in reaction
early
(delta)G ultimately determines the ___ ____ of the reactants and products, but not the ___ ___
final concentration
reaction rate
____: change in free energy from standard state, 1.0M concentrations of substrates and products to equilibrium
(delta)G0
standard state:
___ degrees C
____K
__atm
25
298
1
____ defines (delta)G0 at STP and pH 7.0
(delta)G0’
if free energy of products is lower than substrates, the signs of (delta)G0 and (delta)G0’ will be ____
negative
if free energy of products is higher than substrates, the signs of (delta)G0 and (delta)G0’ will be ____
positive
in ___ reactions, energy is lost
endergonic
in ___, energy is gained
exergonic
(-) delta G: reaction will occur ____ although the rate is ____
spontaneously
unknown
enzymes are ____:
- ___ the rate of the reaction
- are not ____
- bind to _____, lowering ___
- do not change ___
catalysts increase consumed substrates Ea Keq
enzymes are ____
- some are ___ (____)
- many have ___ groups attached to apoprotein forming a ____
- if the prosthetic group is metal, it is a ___
proteins RNAs (ribozymes) prosthetic holoenzymes metalloenzyes
enzymes are __ and ___-____
- enzymes have optimal ___ and ____
- ___ or ___ that denature proteins denature enzyme activity
pH temperature-dependant enzymes temperatures chemicals factors
enzymes are ___
- some are ___, some are ___
specific
absolute
group
some enzymes have ____ specificity, the ability to distinguish between L and D forms of amino acids or sugars
optical
____ ___: binds the reactants and facilitates the reaction
catalytic site
specificity is dictate by the 3D structure of the ___ ___ of the enzyme and the substrate
— requires a minimum of ____ point attachment
catalytic site
3
___ ___: the substrate induces a conformational change in the catalytic site (lock and key)
induced fit
enzymes are saturable; a reaction mixture has a fixed amount of enzyme, so the reaction rate increases with [substrate] to a point, until all enzymes are _____
busy
enzymes are ___ or ___
inhibited
stimulated
_____: increase the rate of reaction
activators/stimulated
_____: decrease the rate of reaction
inhibitors
____ ___: act by competing with the natural metabolite for the active site of the enzyme therefore the are ___ ____
enzyme inhibitors
competitive inhibitors
___ ___: their effect can be overcome by addition of more natural substrate
reversible inhibitors
___ ___: eliminates enzymes function, Vmax is reduced
irreversible inhibitors
coenzymes are ___ ___ required for the catalytic actions of certain enzymes
secondary substrates
coenzymes can be ___ or ___
organic
inorganic
many coenzymes are ___ ___ (especially ___)
vitamin derivatives
B
some coenzymes are ___ ___ of enzymes
prosthetic groups
____: anything that help an enzyme do its function
coenzymes
___ ____ or ___: substances other than substrates which regulate and enzymes activity by binding to the ___ ___ of the enzyme
allosteric effectors or ligands
allosteric site
___ ___: can be catalytic site or another site of enzyme
allosteric site
binding of activator or inhibitor to the allosteric site changes the enzyme ____, especially the catalytic site, altering the reaction rate ____
conformation
exponentially
____: positive allosteric kinetics
acceleration
___: negative allosteric kinetics
deceleration
kinetic plot demonstrates a non linear ___ curve
S
kinetics assesses how ___ of an enzymatic reaction is affected by a host of factors (5 to name a few)
[substrate] coenzymes activators inhibitors pH temperature phase of the moon
experiments are done to obtain info on 3 things
specificity of an enzyme
mechanism of activation/inhibition
____ ____ ___: measures velocity of a reaction, with increasing substrate concentrations, keeping pH and temperature optimum
michaelis-menten equation
V max is…
max velocity of an experimental situation
Km =
the [substrate] that produces a velocity of 1/2 max
how strong affinity an enzyme has for its substrate
the ____ the Km, the ___ the affinity
lower –> higher
higher –> lower
lineweaver-burk (double reciprical) plot…
removes the uncertainty of the Vmax plateau of Michaelis-menten
michaelis-menten an lineweaver-burk are only good for ___-__ kinetics, bc of the additional substrate binding may alter the rate of the reaction
non-allosteric
trivial names of enzymes (2)
papain
chymotrypsin
hybrid name of enzymes
substrate + ‘ase’
descriptive names of enzymes
substrate + description + ase
6 classifications of enzymes
oxidoreductase transferase hydrolase lyase isomerase ligase
____: redox reactions
oxidoreductase
___: transfer groups (other than H) between substrates
transferase
___: break substrates by addition of water
hydrolase
___: break sbstrates without water (leave double bonds)
lyase
____: convert isomers
isomerase
___: ligate with new covalent bonds
ligase
____: ligases that use ATP/GTP as energy sources
synthetase
____: ligases that use other energy (not GTP/ATP)
synthase
4 digit enzyme code:
- 1st number
class number
4 digit enzyme code:
- 2nd number
the first functional group of the substrate to be altered
4 digit enzyme code:
- 3rd number
the second functional group of the substrate to be altered
4 digit enzyme code:
- 4th number
denotes the particular enzyme
increase/decrease enzyme biosynthesis
- at the DNA/RNA level gene ___/____
induction
repression
REGULATION OF ENZYMES - SLIDE 27
aldkjf
____: two or more enzymes that catlyze the same biochemical reactions
isozymes
