Buffer systems, whether inside your body or not, help to control the acidity of a solution. In your body, this is particularly important, as you need a very stable environment both inside and outside the cells with regard to temperature, acidity and other variables. Protein buffer systems help maintain acidity in and around the cells.
In chemistry and biochemistry, the acidity of a solution is called pH. Solutions with low pH -- values less than 7 -- are acidic, while solutions with pH higher than 7 are basic. A pH of 7 is considered neutral. Your body pH is slightly on the basic side of neutral, explain Reginald Garrett and Charles Grisham in their book "Biochemistry," because normal values run around 7.4. The buffer systems in and outside cells help maintain that pH.
Buffers, protein or otherwise, work by consuming small amounts of acid or base added to a solution. For instance, you're constantly producing carbon dioxide, and you burn sugar and other nutrients to produce energy. While you exhale the carbon dioxide eventually, it's in your blood and other body fluids until you do so, and it's acidic. Without buffers, your cellular pH and the pH of fluid outside the cells would fall.
Protein buffer systems depend upon proteins, as opposed to nonprotein molecules, to act as buffers and consume small amounts of acid or base. The protein hemoglobin makes an excellent buffer. It can bind to small amounts of acid in the blood, helping to remove that acid before it changes the blood's pH. Many other proteins act as buffers as well. Proteins containing the amino acid histidine are particularly adept at buffering, explain Mary Campbell and Shawn Farrell in their book "Biochemistry."
Your body utilizes protein buffer systems without your awareness or the need to do anything in particular to promote it. While you need to eat protein to be able to make protein, you need protein for more than just production of buffers -- it helps you maintain all your cells. If you're eating enough protein to maintain health, you're eating enough to maintain your buffer systems.