A Potential, Intracellular Trigger for Removal of Senescent Erythrocyte: Hemoglobin with Methionine Beta (55) D6 Oxidized to the Sulfoxide Derivative

Abstract

Most of the prevalent theories of aging are working hypotheses designed to measure and explain various age-related changes. The basic assumption of the theories commonly referred to as stochastic is that cellular aging may be due to cumulative and deteriorative effects of random events, such as the chemical damages due to free radicals (1). In recent years (since the discovery of superoxide dismutase), oxygen radicals have been invoked to favor debilitating processes, including aging of molecules and cells (1,2). Although oxidation of thioesther groups has long been known in biochemistry, the importance of methyonyl residues as possible targets of oxygen radicals has only recently been recognized (3). Methionyl residues in proteins and peptides can readily be oxidized also in vitro to the sulfoxide derivative by suitable chemical agents, under mild conditions, which do not modify other residues except exposed sulfhydryl groups. Therefore, in view of the effect of the oxidation of methionine in several biological processes (such as aging), it seemed of interest to investigate the functional properties of human hemoglobin with some methionyl groups oxidized by chloramine T.