How do you explain the observation that pepsin, a digestive enzyme found in the stomach, has a high catalytic activity at pH 1.5, while trypsin, an enzyme of the small intestine, has no activity at pH 1.5?

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Accepted Answer

All right. Hello everyone. So this question says that lipase which is an enzyme found in the pancreas exhibits high catalytic activity at ph eight. While Pepsin an enzyme found in the stomach exhibits no catalytic activity at this. Ph Why? So let's talk about enzymes as a whole. Recall that most enzymes are proteins. In fact, the vast majority of enzymes are proteins and enzymes are proteins that catalyze biochemical reactions that take place in our cells in our bodies. Now, because they're proteins, specifically proteins are very sensitive two changes in their structure. This is because proteins have a set of optimal conditions. The structure of a protein is very heavily going to affect its function. So things like ph temperature and the addition of certain reagents are going to affect the structure of the protein and therefore affect its function oftentimes in a negative way, it's going to decrease the function of that protein. And so going back now to enzyme is specifically, if the structural integrity of the enzyme somehow changes, then the activity of the enzyme is of course going to decrease. Now because proteins tend to have such specific optimal conditions. We can understand why certain proteins are only found in certain environments of the body. For example, lipase is an enzyme found in the pancreas. Whereas Pepsin is an enzyme found in the stomach. Now, what's noteworthy about the stomach if you recall is that it contains stomach acid. And so an enzyme like Pepsin has to be able to operate at such a low ph. In fact, the PH is remarkably low at around 1.5 to 2. On the other hand, the pancreas is a little bit more neutral in terms of PH or maybe even slightly basic. Its PH tends to be anywhere between 7.5 to 8. So relatively neutral and a little bit more alkaline, more basic. So because of this drastic difference in the PHS of both environments, we can understand why these proteins are very specialized to these environments. If the Ph of a certain environment is changes too drastically compared to the optimal conditions of a given enzyme, that enzyme is likely to denature or the three dimensional structure of the protein of the enzyme unfolds completely, which of course compromises the function of that protein. And so the main point of this question is to reinforce the fact that enzymes are very specific for their environments. If you change the Ph of the environment, too much that protein, that enzyme can no longer function. And so with that weve arrived at our final answer. So our final answer reads as follows because lipase operates optimally in alkaline environments while Pepsin requires highly acidic environments. And so with that being said, thank you so very much for watching. And I hope you found this helpful.

How do you explain the observation that pepsin, a digestive enzyme found in the stomach, has a high catalytic activity at pH 1.5, while trypsin, an enzyme of the small intestine, has no activity at pH 1.5?

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Enzyme Structure and Function