Increasing the substrate concentration

Prof. Wilson: Correct! If you increase the substrate concentration, then the rate (speed) of the enzymatic activity would increase as well, because there is more substrate for the enzyme to bind to.  

You: There is a limit to this though, right? I remember that this effect plateaus once all active sites are occupied, reaching a saturation point, where further increases in substrate concentration do not enhance activity.

Prof. Wilson: That’s right, well-done! This is an important consideration indeed! I think we are just about ready to go on with our experiment, one more concept that we need to revise before we get to the fun part of carrying out the experiment! Let’s also consider the effect of pH and temperature on enzyme function. Are these important?

James: Yes, of course. The optimal pH and temperature are important for enzyme action. The optimal conditions vary based on the location and function of each enzyme. For example, the optimal pH for pepsin, which is found in the acidic environment of the stomach is much lower than the optimal pH for pancreatic lipase, which is found in the duodenum. 

Prof. Wilson: I couldn’t have said it better myself, James, that is correct. You may remember this graph from the book that shows that the optimal pH for enzymes A and B differ. 

                                            Optimal pH and Temperature 

Reference: Adapted from Furry, L. A., Cain, M. L., Wasserman, S. A., Minorsky, P. V., Orr, R. B., & Reece, J. B. (2020). Campbell Biology (12th ed.). Pearson.