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Name: aissa
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my question is what is the effect of ph on enymes. according to the ph meter scale:ph10 bleach, ph7 sodium phosphate, ph6 tap water and ph3 lemon juice, which of these have a zero effect on enzymes? I'm doing a lab class that i missed as a result cant answer the question

The question is: Which enzymes? Most human enzymes work at a optimal pH of 7.4, but other enzymes work at many different pH ranges.

Steve Sample

Hi Aissa,

It depends on what the enzyme is. The condition that most closely mirrors the environment that the enzyme was designed for will have "zero effect".

Donald Yee Ph.D.

Instead of answering this question for you, I am going to help you along the way with your though process. I prefer to address this question in this manner because science is full of similar problems. What you need to consider is the natural functional / biological environment of your enzyme. That is, there are two major components to consider in this question, the pH at which enzymes function and the ionic contents of your solution. Any changes to that standard system are going to effect your enzyme's function.

Saundra Sample

Each enyzme has it's own pH optimum. Some can do their work in a broad range of pHs, others are very sensitive and only work at the exactly right pH. Most enzymes work best in or around neutral pH, say between pH 7 and 8. However, some enzymes are needed in conditions of extreme pH, and use that pH as an optimum for activity. For instance, pepsin that is needed in the stomach has an acidic optimum and would work in lemon juice. Other enzymes work best in alkaline conditions. A solution with a buffered pH (like sodium phosphate) will be better for enzymatic activity than a non-buffered solution (tap water) because enzymes are proteins, and these can themselves influence the pH of the solution if this is not buffered. Stangely enough, an enzyme that would turn water acidic may have an optimum at alkaline pH. So, in conclusion, each enzyme has it's own pH optimum.

Dr. Wassenaar

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