Enzymes are biological catalysts that help to promote biological chemical reactions in living systems.
Enzymes will have a secondary structure and when there are changes in pH this disrupts the ionic bonds in the secondary structure of the enzyme and therefore will disrupt the enzymes tertiary structure.
The disruption of bonds can cause the enzymes active site to change and therefore it can no longer efficiently carry out its task and so certain metabolic reactions will be affected.
Buffers ensure that the bodies pH remains at a constant that is comfortable and is close to the enzymes optimal pH point to ensure that all metabolic reactions occur properly.
"Buffers react with small amounts of acid and alkali to ensure that pH remains constant"
Hope that helps :)
