P69 Oxygen reactivity in the sulfmyoglobin formation

Abstract

For many years hydrogen sulfide (H2S) has been considered a toxic gas, but recent studies have presented it as a signaling gas that is involved in many physiological reactions. However, when the human body is exposed to high H2S concentrations, a sulfur atom can bind to the heme group of hemoglobin (Hb), forming an Hb derivate called sulfhemoglobin (SHb). The presence of the Histidine amino acid residue in the E7 position and the ferryl species formed by oxygen (O2), and/or hydrogen peroxide are required for its formation. Sulfhemoglobin produces a condition called Sulfhemoglobinemia, which decreases the Hb ability of O2 transport. Our goal was to evaluate the SHb complex formation with different O2 concentrations, in order to determine a SHb mechanism when formed with O2. Myoglobin (Mb) was used for experiments because it has a similar active site structure as Hb and both bind oxygen. Since it was determined that the oxyMb complex was totally formed with a 1:6 proportion (Mb: O2), O2 concentration variations were done in 1:6, 1:83, and 1:160. The SMb complex formation was evaluated by UV–vis 300–800 nm region following characteristic 620 nm sulfheme band through a 24 h kinetic analysis. Results indicated that the O2 is involved in the process of the SMb complex formation leading to the transient deoxy specie and depending on the O2concentration, the equilibrium reaction toward the deoxy specie may change.