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ReactionsReactions
Substrates (reactants) -- A B C D Products -- P Q R S Enzyme -- E F G Inhibitors -- I J Activators
Metal ion -- Mn+/-
Other -- X Y Z
Substrates (reactants) -- A B C D Products -- P Q R S Enzyme -- E F G Inhibitors -- I J Activators
Metal ion -- Mn+/-
Other -- X Y Z
EnzymesEnzymes
Stable: when isolated from the rest of the reaction components, it has a long half-life with respect to the assay times scale, and reactants add to it in a bimolecular step.
Transitory: when isolated from the rest of the reaction components its half-life is short relative to the assay time scale.
Central: if the active site is completely filled and kinetically competent
Noncentral: if not.
Stable: when isolated from the rest of the reaction components, it has a long half-life with respect to the assay times scale, and reactants add to it in a bimolecular step.
Transitory: when isolated from the rest of the reaction components its half-life is short relative to the assay time scale.
Central: if the active site is completely filled and kinetically competent
Noncentral: if not.
Kinetic MechanismKinetic Mechanism
Sequential: all reactants must be bound to an enzyme before any reaction occurs.
Ping-Pong: a product is released between the addition of two substrates
Ordered: there is an obligatory order fo addition of reactants to an enzyme and /or release of products from enzyme.
Random: there is not.
Sequential: all reactants must be bound to an enzyme before any reaction occurs.
Ping-Pong: a product is released between the addition of two substrates
Ordered: there is an obligatory order fo addition of reactants to an enzyme and /or release of products from enzyme.
Random: there is not.
Kinetic ConstantsKinetic Constants
Michaelis constant (Km) is defined as the concentration of reactant that gives half the maximum rate at saturating concentrations of all other reactants and with products maintained at zero concentration.
Michaelis constant (Km) is defined as the concentration of reactant that gives half the maximum rate at saturating concentrations of all other reactants and with products maintained at zero concentration.
Rate ConstantsRate Constants
Microscopic: associated rate constants of the individual steps in a reaction scheme
First-order Second-order Macroscopic:
Microscopic: associated rate constants of the individual steps in a reaction scheme
First-order Second-order Macroscopic:
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Michaelis-MentenMichaelis-Menten
1
212
2
1
1
; :Haldane-Briggs
P E ES S E
k
kkKkk Mcat
k
k
k
−==
+⏐ →⏐⏐ ⏐←⏐ →⏐+
−
−
[ ][ ] [ ][ ][ ] [ ]
[ ] [ ][ ][ ] Menton)(MichaelisS
SE:0P lim if
; ;; ;
eqn) (general PS1
PESE
e)(reversibl P E ES S E
00
2
2
212
1
21
00
2
2
1
1
−+
=→
=+
==−
=
++
−=
+⏐ ⏐←⏐ →⏐⏐ ⏐←
⏐ →⏐+
−−−
−−
K
kv
Kkkk
kkKKkk
k
kkK
KK
kkv
mS
cat
mPSmPmSSmS
mPmS
PS
k
k
k
k
[ ][ ] [ ][ ][ ] [ ]
( )form) general samebut d,complicate (more
;; ;
eqn) general (same PS1
PESE
)(multistep P E EP ES S E
323121
321
3221
323121
00
3
3
2
2
1
1
L=++
=++++
=
++−
=
+⏐ ⏐←⏐ →⏐⏐ ⏐←
⏐ →⏐⏐ ⏐←⏐ →⏐+
−−−−−
−−−
−−−
mPSmS
mPmS
PS
k
k
k
k
k
k
Kkkkkkk
kkkk
kkkkkkkkkk
K
KKkk
v