Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, f...

Question

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?
c. running the reaction at 0 °C

c. running the reaction at 0 °C

Accepted Answer

All right. Hello everyone. So this question says that chymotrypsin is an enzyme that hydrolyzes peptide bonds and proteins with optimal activity in the small intestine at a ph of 7 to 8. How would running the reaction at a temperature of five °C affect the rate of a reaction catalyzed by chymotrypsin. So here we have four different answer choices labeled A through D which we'll discuss in greater detail later in this video for now, let's just recall a few things about enzymes. The main one being that the vast majority of enzymes are proteins. The reason why this matters is because the structure of a protein heavily informs the function of said protein. So because the structure of an enzyme, he informs the function of the enzyme, it is going to be very sensitive to changes in the structure. And so factors like temperature and ph could have an effect on the structure and therefore the function. Now, when it comes to temperature, oftentimes we remember that an increase in temperature often leads to the unfolding of the enzyme itself. This is because the higher temperature is going to interact or is going to interfere with the intermolecular forces holding the three dimensional structure of the enzyme together. So once you lose that structure, you lose the function, right, the enzyme is no longer able to perform its function if it has lost its structure. But what happens then when you decrease the temperature of the enzyme, what is that going to do to the activity of the reaction? Well, it's important to mention that temperature is energy, heat is energy. So when you decrease the temperature of the system, what you're doing is decreasing the kinetic energy that both the enzyme and the substrate have. So when both the enzyme and the substrate have less kinetic energy, what happens? Well, namely, there are going to be less collisions between the two and if there are less collisions between the enzyme and the substrate, then the reaction that's supposed to be catalyzed by the enzyme is less likely to occur. And if it's less likely to occur, then the rate of the reaction goes down. So when it comes to really low temperatures, we're not necessarily increasing the structure or affecting the structure of the enzyme. But we are impacting the kinetic energy present, making collisions less likely and therefore reducing the rate. So extreme deviations from the optimal temperature of an enzyme will impact enzyme stability and function. So this brings us now to our answer choices. Option A says that that the reaction rate will decrease because the enzyme becomes more viscous at lower temperatures hindering substrate interaction. This generally isn't true. Right? Because when it, when it comes to lower temperatures, we're more concerned with the reduction in kinetic energy, the reduction in molecular motion not viscosity option B. On the other hand says the reaction rate will decrease because the lower temperature reduces the kinetic energy of molecules leading to fewer collisions between the enzyme and substrate. This is correct, right, because lower temperature isn't really going to impact the structure of the enzyme, but it is certainly going to impact the energy kinetic energy that's present. Now, our correct answer is going to be B but for the sake of completeness, let's go over C and D option C says that the reaction rate will remain unchanged because enzyme activity is not significantly affected by temperature changes. This is not true, right? Because as mentioned before the reaction rate will definitely decrease because enzyme activity is significantly affected by a change in temperature, specifically a change in temperature. Beyond the optimal range of that enzyme option D says that the reaction rate will decrease because the enzyme's optimal temperature is below five °C leading to a loss of enzyme activity. And this is not correct either. W why? Because Kimmo Trypsin is an enzyme found in our small intestines, which means that the ideal temperature of chal trypsin is most likely going to be body temperature. So that's actually around 37 °C, definitely not five °C. So here just to reiterate our correct answer is going to be option B in the multiple choice and there you have it. So with that being said, thank you so very much for watching and I hope you found this helpful.

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?
c. running the reaction at 0 °C

Key Concepts

Enzyme Activity and Temperature

pH and Enzyme Function

Reaction Rate and Substrate Concentration

Watch next

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?c. running the reaction at 0 °C

Key Concepts

Enzyme Activity and Temperature

pH and Enzyme Function

Reaction Rate and Substrate Concentration

Watch next

Pepsin, an enzyme that hydrolyzes peptide bonds in proteins, functions in the stomach at a pH optimum of 1.5 to 2.0. How is the rate of a pepsin-catalyzed reaction affected by each of the following conditions?
c. running the reaction at 0 °C