Proteins can catalyze reactions {enzymatic reaction}|.
types
Enzymes can catalyze hydrogen-ion interactions. They can catalyze anion and cation formation. They can catalyze chelation. They can catalyze charge-transfer coupling. They can catalyze organic-acid formation and breakdown. They can catalyze proton abstractions. They can catalyze Schiff-base reactions.
They can catalyze configuration inversion.
They can catalyze phosphate transfer. They can catalyze pyrophosphate incorporation. Adenylate cyclase can catalyze cAMP-mediated reactions. They {guanylate cyclase} can catalyze cGMP-mediated reactions. They can catalyze transfers.
They can catalyze oxidation. They can catalyze reduction.
They can catalyze metal-bridge formation. They can catalyze metal binding.
They can catalyze acetylation. They can catalyze acylation.
They can catalyze free-radical reactions.
They can catalyze ring breaking and forming.
They metabolize amines, amides, aldehydes, histidines, imidazoles, ketones, nitroxides, oxides, serines, thiols, and thiol esters. They metabolize lipoproteins, carbohydrates, membranes, ion channels, enzyme proteins, lipids, and nucleic acids.
process
Enzymatic reactions can involve active-site directed agents, induced fit, steric effects, and molecular vibrations.
process: reversible
In enzyme-catalyzed chemical reaction, substrate and enzyme quickly and reversibly bind together to make transition state {enzyme-substrate complex}. The reversible reaction has forward and backward reaction rates {Michaelis-Menten rate equation, enzymatic reaction}.
process: irreversible
Transition state slowly and irreversibly separates to reform enzyme and make product. The irreversible reaction has only forward reaction rate.
process: overall
Reaction first part reaches equilibrium quickly, and intermediate concentration quickly becomes constant {steady state, equilibrium}. At steady state, intermediate concentration change over time is zero, free-enzyme concentration is much less than substrate concentration, and intermediate concentration equals total enzyme concentration.
d[ES]/dt = 0 = f1*[E]*[S] - b1*[ES] - f2*[ES]. [E] = [ET] - [ES]. [E] << [S], so [ES] = [ET]. [ES] is enzyme-substrate-complex concentration. [ET] is total-enzyme concentration. [E] is enzyme concentration. f1 is reversible-reaction forward rate. b1 is reversible-reaction backward rate. f2 is irreversible-reaction forward rate.
process: rate
Substrate depletion rate equals product creation rate: product amount divided by time in seconds. Rate is reaction velocity. Rate depends on forward rate, of making product from intermediate, times intermediate concentration.
Reaction rate can be constant {constitutive reaction rate}. Reaction rate can depend on another-molecule concentration {induced reaction rate}.
Product formation rate depends on maximum possible rate, substrate concentration, and forward and back reaction rate constants.
Maximum velocity depends on enzyme concentration and rate constant. Maximum rate {maximum velocity} {Vmax} equals forward reaction rate times total enzyme concentration.
Rate constant for whole Michaelis-Menten equation depends on all three rates: Km = (b1 + f2) / f1. Reaction velocity v depends on rate constant Km, substrate concentration S, and maximum velocity Vmax: v = (Vmax * [S]) / (Km + [S]).
Physical Sciences>Chemistry>Biochemistry>Protein>Chemical Reaction
5-Chemistry-Biochemistry-Protein-Chemical Reaction
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Date Modified: 2022.0224