Protein oxidation and turnover

All biomacromolecules are faced with oxidative stress, Oxidation of a prote in molecule always induces inactivation of the molecule and introduces a ta g to that molecule, These modified protein molecules are prone to degradati on in vivo by the proteasome system, Coupling of protein modification and d egradation of chemically modified proteins is one of the normal protein tur nover pathways in vivo, We call this a 'chemical apoptosis' process, which is one of the early manifestations of programmed cell death, Impairment of the proteasome system leads to accumulation of modified nonfunctional prote ins or 'aged proteins' that might cause various clinical syndromes includin g cataractogenesis, premature aging, neurological degeneration and rheumato id disease, The metal-catalyzed oxidation of biomacromolecules provides an excellent artificial aging system in vitro. The system is very useful in th e characterization of structure and function relationships of proteins (enz ymes), especially in those containing metal binding domain(s), because the oxidation is always followed by an affinity cleavage at the metal binding s ite(s) that allows easy identification and further characterization. Copyri ght (C) 2000 National Science Council, ROC and S. Karger AG, Basel.