Enzymes and pH

[bidiboom]

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Hi people,

Arent the enzymes work best at 7.4, or more precisely in the range of 7.35-7.45? There is a question about it and the answer is 7.2. I would not pick this as the correct answer, but to the book, it is! Am I wrong?

Thank you for any answer..

 

[SaintJude]

Yeah, most enzymes have an optimal range of around 7.2 (but a lot of sources say 7.2-7.4). But there are plenty of enzymes in the body who work at completely different pHs like pepsin, whose optimal pH is 2. Kind of a weird question. What test prep are you using?

 

[bidiboom]

Thank you 🙂 This is an SAT Biology question actually, not MCAT.
Why are those two different, I mean, enzyme activity range (7.20-7.40) and body pH (7.35-7.45)? Do you have any idea?

 

[mcloaf]

Hi people,

Arent the enzymes work best at 7.4, or more precisely in the range of 7.35-7.45? There is a question about it and the answer is 7.2. I would not pick this as the correct answer, but to the book, it is! Am I wrong?

Thank you for any answer..

This is not necessarily true. There are all sorts of enzymes that have different optimal pH ranges, it is a function of the environment in which the enzyme needs to work. Pepsin, for example, needs an optimal pH of around 2 because it works in the acidic environment of your stomach.

 

[bidiboom]

This is not necessarily true. There are all sorts of enzymes that have different optimal pH ranges, it is a function of the environment in which the enzyme needs to work. Pepsin, for example, needs an optimal pH of around 2 because it works in the acidic environment of your stomach.

Ok but pepsin is a special case, regularly other enzymes work in normal body pH range.. I mean I have known that way until now. Other than pepsin I dont know another enzyme which works at a different pH, is there any other?

 

[mcloaf]

Ok but pepsin is a special case, regularly other enzymes work in normal body pH range.. I mean I have known that way until now. Other than pepsin I dont know another enzyme which works at a different pH, is there any other?

Yes, there are plenty. Alkaline phosphatases for example. Every enzyme has a unique optimal pH range, which, as I said before, is going to be dependent on the environment in which it functions. There's no reason to assume that all enzymes function more or less at human physiological pH.

 

[bidiboom]

Yes, there are plenty. Alkaline phosphatases for example. Every enzyme has a unique optimal pH range, which, as I said before, is going to be dependent on the environment in which it functions. There's no reason to assume that all enzymes function more or less at human physiological pH.

hmm.. ok, now its clear.. thank you very much 🙂