Buffers

Fundamentals

Concepts

Math Problems

Redox

Chirality

Entropy

Fluids inside biological organisms must be maintained at a constant pH for the health of the organism. That is because these fluids, whether blood, cytosol, lymph, bile, etc., contain enzymes that carry out the reactions that support life, and each of these enzymes only has a certain pH range within which it can function effectively. This is called the pH dependency of the enzyme. If the pH is too high or too low, the amino acid residues important for catalysis might be in the wrong protonated state for catalysis, or the enzyme's conformation could change, rendering it nonfunctional. Shown at right is a graphic for a fictional enzyme that is very similar to the pH dependence of trypsin. Other enzymes in the same organism might have a very different dependence. For example, pepsin has optimal activity at a pH of 2, because it is a digestive enzyme and has to be active in acidic digestive fluids.

If the pH of biological fluids is so important, how does an organism make sure its fluids are all kept at the proper pH for the correct functioning of all of its enzymes, even if the organism ingests material that is acidic or basic? The answer is that all the biological fluids are buffered. Buffers are solutions that are resistant to changes in pH, even if acid or base is added to the solution. Because enzymes are so pH-sensitive, not only for their activity but also for their stability in solution, buffers are very important for biochemical research. In a lab, researchers keep all of their proteins in buffered solutions. Therefore, beginning biochemists need to understand how buffers work in the body and how to make them in the lab.

This difficult concepts section is a primer to help you grasp buffers to a level of understanding needed for introductory biochemistry. Go through the subsections in order to get the best instruction:

• Fundamentals - teaches the basics of how buffers work.
  
  
• Concepts - shows the application of buffers to biochemistry, both in nature and in the laboratory.
  
  
• Math problems - step-by-step presentation on how to successfully design a buffer for use in the laboratory.