Term
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Definition
one or
more inorganic ions, such as Fe2, Mg2,
Mn2, or Zn2 |
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Term
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Definition
transient
carriers of specific functional groups |
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Term
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Definition
coenzyme or metal ion
that is very tightly or even covalently bound to the enzyme
protein |
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Term
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Definition
A complete,
catalytically active enzyme together with its bound
coenzyme and/or metal ions is called a |
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Term
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Definition
| protein part of such an holoenzyme |
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Term
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Definition
| increase the rate of a reaction and lowering activation energies. do not affect reaction equilibria. |
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Term
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Definition
starting point for either the forward or the reverse
reaction |
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Term
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Definition
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Term
|
Definition
molecule that is bound in the
active site and acted upon by the enzyme |
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Term
| E+S <=> ES <=> EP <=> E+P |
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Definition
| where E, S, and P represent the enzyme, substrate, and product. ES and EP are complexes of the enzyme with the substrate and with the product |
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Term
| free energy of P is lower than S |
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Definition
| ΔG is negative and equilibrium favors P. |
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Term
| free energy of P is greater than S |
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Definition
| ΔG is positive and equilibrium favors S. |
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Term
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Definition
| top of the energy hill is a point at which decay to the S or P state is equally probable |
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Term
|
Definition
difference
between the energy levels of the ground state and
the transition state |
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Term
higher
activation energy corresponds to a |
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Definition
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Term
| Reaction rates can be increased by |
|
Definition
raising the temperature
and/or pressure, thereby increasing the number of
molecules with sufficient energy to overcome the energy
barrier |
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Term
| equilibrium constant, Keq |
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Definition
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Term
relationship between Keq
and G, G = ? |
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Definition
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Term
| rate of any reaction is determined by |
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Definition
the concentration
of the reactant (or reactants) and by a rate constant, k |
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Term
For the unimolecular
reaction S→P, the rate (or velocity) of the reaction, V = ? |
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Definition
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Term
|
Definition
rate depends only on the concentration
of S |
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Term
If a first-order
reaction has a rate constant k of 0.03 s^-1,
this means that |
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Definition
3% of the available
S will be converted to P in 1 s. |
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Term
reaction rate depends on the concentration
of two different compounds, or if the reaction is between
two molecules of the same compound |
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Definition
| second-order rate constant |
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Term
| second order rate equation |
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Definition
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Term
energy derived from
enzyme-substrate interaction |
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Definition
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Term
driving force
for enzymatic catalysis |
|
Definition
| weak binding interactions between the enzyme and the substrate |
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Term
|
Definition
the ability
to discriminate between a substrate and a competing
molecule |
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Term
|
Definition
restriction in the relative motions of
two substrates that are to react, constraining, increases rate of reaction |
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Term
| general acid-base catalysis |
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Definition
| aminoacid side chains can act as proton donors and acceptors |
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Term
|
Definition
covalent bond is formed between the enzyme and the substrate
A—B+X: => A—X+B H2O=> A+X:+B |
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Term
|
Definition
| Ionic interactions between an enzyme-bound metal and a substrate can help orient the substrate for reaction |
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Term
|
Definition
to determine the rate of a reaction and
how it changes in response to changes in experimental
parameters |
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Term
key factor affecting the rate of a reaction catalyzed by
an enzyme |
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Definition
| the concentration of substrate, [S]. |
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Term
|
Definition
| The substrate concentration at which V0 is half maximal, Km |
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Term
At relatively low concentrations
of substrate, V0 increases |
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Definition
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Term
| At higher substrate concentrations, V0 increases by |
|
Definition
smaller and smaller amounts in response to
increases in [S] |
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Term
Michaelis-Menten equation is Relationship between Substrate Concentration and
Reaction Rate |
|
Definition
the rate equation for a one-substrate enzyme-catalyzed reaction
V0 = Vmax[S]/ Km+[S] |
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Term
Michaelis-Menten kinetics:
Km = [S] when |
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Definition
| the initial velocity V0 is 1/2 Vmax |
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Term
|
Definition
| 1/V0= (Km/Vmax[S]) + (1/Vmax) |
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Term
| Lineweaver-Burk equation yields a straight line which the slope is |
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Definition
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Term
best way to compare the catalytic efficiencies of
different enzymes |
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Definition
compare the ratio
kcat/Km for the two reactions |
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Term
|
Definition
competes with the substrate
for the active site of an enzyme |
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Term
in the presence of a competitive inhibitor, the Michaelis-
Menten equation (Eqn 6–9) becomes |
|
Definition
V0 = Vmax[S]/ aKm+[S]
where a = 1+[I]/Ki |
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Term
mixed inhibitorbinds to
either E or ES. The rate equation describing mixed
inhibition is |
|
Definition
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Term
|
Definition
| noncompetitive inhibition |
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Term
|
Definition
bind covalently with or destroy a functional group on an
enzyme that is essential for the enzyme’s activity |
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Term
|
Definition
mechanism-based inactivators,
because they hijack the normal enzyme reaction
mechanism to inactivate the enzyme |
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Term
|
Definition
| lyases, ligases, hydrolases, transferases |
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Term
|
Definition
| biocytin, coenzyme a, Lipoate |
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Term
| idea was proposed by Linus Pauling in 1946 |
|
Definition
enzyme active sites are complimentary to the transition
state of the reaction and bind transition states better than substrates |
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Term
|
Definition
| preferential interactions with TS |
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Term
| examples of Covalent Catalysis: In Enzymes |
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Definition
Proteases and peptidases
chymotrypsin, elastase, subtilisin |
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Term
| Rate of enzymatic reaction is affected by |
|
Definition
Enzyme
Substrate
Effectors
Temperature |
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Term
| in enzyme mechinism plots Intersecting lines indicate |
|
Definition
| a ternary complex is formed in the reaction |
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Term
| in enzyme mechinism plots parallel lines indicate |
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Definition
| Ping-Pong (double-displacement) pathway |
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Term
| Reversible inhibitor can bind |
|
Definition
To the free enzyme and prevent the binding of the substrate
To the enzyme-substrate complex and prevent the reaction |
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Term
| Competitive inhibition plot |
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Definition
| Lines intersect at the y-axis |
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Term
| unCompetitive inhibition plot |
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Definition
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Term
|
Definition
| Lines intersect left from the y-axis |
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Term
|
Definition
apparent Vmax = Vmax
apparent Km = Km |
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Term
| inhibitor type: competitive |
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Definition
apparent Vmax = Vmax
apparent Km = aKm |
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Term
| inhibitor type: uncompetitive |
|
Definition
apparent Vmax = Vmax/a'
apparent Km = Km/a' |
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Term
|
Definition
apparent Vmax = Vmax/a'
apparent Km = aKm/a' |
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Term
|
Definition
| Irreversibly inactivates the trans-peptidase |
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Term
|
Definition
exhibit increased or decreased
catalytic activity in response to certain signals. |
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Term
|
Definition
Allosteric enzymes function
through reversible, noncovalent binding of regulatory
compounds called allosteric modulators or allosteric effectors, |
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Term
allosteric modulators or allosteric
effectors |
|
Definition
small metabolites or
cofactors |
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Term
|
Definition
Buildup of the
end product ultimately slows the entire pathway |
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Term
|
Definition
| á-D-glucose and B-D-glucose |
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Term
|
Definition
Enzyme undergoes a conformational change when a substrate binds. This
conformation change can be used to bring critical catalytic residues into proper position
for reaction or can be used to help shield transition state from other chemicals in the
system that could interfere with the reaction. |
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Term
| Entropy ReductionEntropy Reduction |
|
Definition
Restriction of the movement of substrate, holding the substrate in
one place and aligning it properly though many weak interactions the enzyme limits the
substrate to a conformation where the reaction can occur, and prevents it from
assuming other conformations the cannot react or that would take a higher energy to
react |
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Term
|
Definition
Weak enzyme substrate interactions can replace many of the substrate
solvent interactions and, essentially take the substrate out of solution. This is
necessary because water can interfere in many reactions to produce incorrect products.
And some reactions that are hydrophobic by nature cannot be performed in an aqueous
environment |
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