|MadSci Network: Biochemistry|
Hello, I apologize for the slow response. This is largely taken from Styer's Biocemistry text, 3rd Ed., Page 422 Catalase does not directly and deliberately affect any particular enzyme pathway. Its purpose is is to remove toxic peroxide that is derived mainly as a byprduct of the production of ATP in the mitochondria from the complete oxidation of glucose. Peroxide is an indirect product of the occasional incomplete reduction of oxygen to water. The stepwise transfer of elections to oxygen is tightly controlled by a series of protein complexes in the inner mitochondrial membrane. However, at a low rate, an electron is transferred from a metal ion inside one of the catalysts to an oxygen molecule to produce superoxide. Superoxide is very reactive and can spontaneously damage a nearby protein. It can also be spontaneously or enzymatically converted to hydrogen peroxide, a less reactive but still damgerous molecule to have in the cell (see Stryer, noted above). Catalases are used to scavenge for and destoy this peroxide. It is also deliberately produced in a few cases, most notably by neutrophils and macrophages to destroy bacteria. However, catalase seems to be around mostly to scavenge for peroxide that is a byproduct of the oxidative phosphorylation process. Superoxide and peroxide are dangerous because they are very reactive and can oxidize a large number of substances including side chains of proteins and lipid derivatives that are a part of the membrane, thus damaging them. DNA bases are also susceptible to oxidation by peroxide. Regards, Jeff
Try the links in the MadSci Library for more information on Biochemistry.