Competitive inhibitors compete for the same binding site as the enzyme substrate. They make the enzyme appear to bind substrate less well, appear to increase Km, without altering the Vmax. This is because adding large amount of substrate swamps out the inhibitor. Noncompetitive inhibitors don't alter substrate binding but prevents catalysis. They are recognized by their decrease of Vmax without an effect on Km.
Physiological inhibitors are normally of the allosteric type.
This is because nature has evolved the enzymes to contain binding sites for regulatory molecules. Really good pharmacological agents either mimic the transition state of the normal substrate of the enzyme, e.g., statins like pravostatin that inhibit HMG-CoA reductase, or form covalent adducts to the enzyme to kill them, e.g., fluorouracil action on thymidylate synthase. J. Proteolysis is the process of hydrolyzing peptide bonds. It is an important physiological process. The pH of cells and serum is maintained by buffering.