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The induced fit model is a development of the lock-and-key model and assumes that an active site is flexible and changes shape until the substrate is completely bound. 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.
Hexokinase has a large induced fit motion that closes over the substrates adenosine triphosphate and xylose. Binding sites in blue, substrates in black and Mg 2+ cofactor in yellow. (The different mechanisms of substrate binding. The classic model for the enzyme-substrate interaction is the induced fit model. [4]
For example, bacteria may become resistant to antibiotics such as penicillin because enzymes called beta-lactamases are induced that hydrolyse the crucial beta-lactam ring within the penicillin molecule. [93] Another example comes from enzymes in the liver called cytochrome P450 oxidases, which are important in drug metabolism.
The concept of two distinct symmetric states is the central postulate of the MWC model. The main idea is that regulated proteins, such as many enzymes and receptors, exist in different interconvertible states in the absence of any regulator. The ratio of the different conformational states is determined by thermal equilibrium. This model is ...
During the course of the docking process, the ligand and the protein adjust their conformation to achieve an overall "best-fit" and this kind of conformational adjustment resulting in the overall binding is referred to as "induced-fit". [5] Molecular docking research focuses on computationally simulating the molecular recognition process.
In biochemistry, a conformational change is a change in the shape of a macromolecule, often induced by environmental factors. A macromolecule is usually flexible and dynamic. Its shape can change in response to changes in its environment or other factors; each possible shape is called a conformation, and a transition between them is called a ...
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 sequential model (also known as the KNF model) is a theory that describes cooperativity of protein subunits. [1] It postulates that a protein's conformation changes with each binding of a ligand, thus sequentially changing its affinity for the ligand at neighboring binding sites. It gives one explanation for cooperative binding.