The lock and key theory on enzymes has shortcomings because it is unable to explain the stability of the enzyme when the enzyme reaction points are switched, then the induction theory is able to answer the shortcomings of the padlock theory. So, does the theory of induction fit actually have flaws? If so, what are the shortcomings of induction fit theory? And of the two theories, which one theory better explains how enzymes work? Thank you.
Enzymes simply use the substrate to convert to product. Therefore, in enzymatic environment you can find enzyme alone (E) , enzyme with substrate (ES) and enzyme with product (EP). For enzymes to be effectively functional they should have certain interactions with the substrate, otherwise they will not bind to substrate. As substrate bins to enzyme, the catalytic triad of the active site of the enzyme should change their conformation to enable the catalytic activity to happen. This conformational change enable the breakage or formation of new bonds easily. Once the enzymatic reaction is completed the product will be formed and this product will have less favorable interactions with the active site of enzyme and it will leave the enzymes active site. Induced fit model can be used to describe this conformational changes and to explain the activity of enzymes on the substrate.
The lock and key theory does fit, however it does not explain the power of inhibitory molecules or stable analogs or transition state analogs to the model. In this way we use the induction fit model which explains why there are subbtle changes on the lock and key theory. We cannot explain why there are changes in affinity or why there are changes in the adjustion of both molecules. It does not explain allosteric inhibition (and only subbtle modifications of the lock and key theory do) and this is why we use the induction fit model.
It may have flaws but maybe almost none. The models in enzymology not michaelis menten may be why we mention flaws
Thank you so much for reply my question. I now understand about that two theory. The induction fit theory can be used to describe this conformational changes and to explain the activity of enzymes on the substrate and the lock and key theory does not explain the power of inhibitory molecules or stable analogs or transition state analogs to the model. And it may not have flows if the enzym follow michaelis menten rules.
The induction fit theory explain theory explains better how the enzyme works.
Okay, thank you for reply. After all of discussion, i agree with @Amarjit K Nath 's statement that induction fit theory explain better.
Irvan Adi Maulana Dear, the theory of induction fit is better explain the working mechanism of the enzymes. All enzymes are works at specific pH and ambient temperature and the induction fit theory explain the better working mechanisms by providing favorable environment.
In the lock-and-key model, the enzyme-substrate interaction suggests that the enzyme and the substrate possess specific complementary geometric shapes that fit exactly into one another. Like a key into a lock, only the correct size and shape of the substrate (the key) would fit into the active site (the keyhole) of the enzyme (the lock). It shows the high specificity of enzymes. However, it does not explain the stabilization of the transition state that the enzymes achieve. The induced-fit model suggests that the active site continues to change until the substrate is completely bound to the active site of the enzyme, at which point the final shape and charge are determined. Unlike the lock-and-key model, the induced fit model shows that enzymes are rather flexible structures.
https://www.biologyonline.com/dictionary/lock-and-key-model
https://www.biologyonline.com/dictionary/induced-fit-model
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