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The favoured model for the enzyme–substrate interaction is the induced fit model. [53] This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding.
The model is used in a variety of biochemical situations other than enzyme-substrate interaction, including antigen–antibody binding, DNA–DNA hybridization, and protein–protein interaction. [ 17 ] [ 18 ] It can be used to characterize a generic biochemical reaction, in the same way that the Langmuir equation can be used to model generic ...
When used to model enzyme rates in vivo , for example, to model a metabolic pathway, this representation is inadequate because under these conditions product is present. As a result, when building computer models of metabolism [ 1 ] or other enzymatic processes, it is better to use the reversible form of the Michaelis–Menten equation.
The classic model for the enzyme-substrate interaction is the induced fit model. [3] This model proposes that the initial interaction between enzyme and substrate is relatively weak, but that these weak interactions rapidly induce conformational changes in the enzyme that strengthen binding.
This model is similar to a person wearing a glove: the glove changes shape to fit the hand. The enzyme initially has a conformation that attracts its substrate. Enzyme surface is flexible and only the correct catalyst can induce interaction leading to catalysis. Conformational changes may then occur as the substrate is bound.
The Michaelis–Menten Model can be an invaluable tool to understanding enzyme kinetics. According to this model, a plot of the reaction velocity (V 0) associated with the concentration [S] of the substrate can then be used to determine values such as V max, initial velocity, and K m (V max /2 or affinity of enzyme to substrate complex). [4]
Another example comes from enzymes in the liver called cytochrome P450 oxidases, which are important in drug metabolism. Induction or inhibition of these enzymes can cause drug interactions. [93] Enzyme levels can also be regulated by changing the rate of enzyme degradation. [1]: 30.1.1 The opposite of enzyme induction is enzyme repression.
These are called transient interactions. For example, some G protein–coupled receptors only transiently bind to G i/o proteins when they are activated by extracellular ligands, [10] while some G q-coupled receptors, such as muscarinic receptor M3, pre-couple with G q proteins prior to the receptor-ligand binding. [11]