Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Enzymes and pH
Name: aissa
Location: N/A
Country: N/A
Date: N/A


Question:
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



Replies:
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".

Don
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



Click here to return to the Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (help@newton.dep.anl.gov), or at Argonne's Educational Programs

NEWTON AND ASK A SCIENTIST
Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory