Photochemical reduction of methemoglobin and methemoglobin derivatives

Abstract

Publisher Summary Hemoglobin solutions that must be stored for long periods of time must be kept either at very low temperatures or in the complete absence of oxygen, or both. These are conditions are not easy to achieve. The spontaneous oxidation to methemoglobin can be especially bothersome when solutions of precious hemoglobin variants or hemoglobin derivatives need to be stored for an extended time. One is thus often faced with the problem of having to reduce any methemoglobin that has formed in hemoglobin preparations before valid studies with the hemoglobin can be initiated. There are various procedures for the reduction of methemoglobin present in hemoglobin preparations that use a variety of reducing agents, such as dithionite, ascorbate, 5-hydroxyanthranilic acid, and iron salts. However, the direct reduction of methemoglobin with a reducing agent sometimes presents difficulties. The reduction of methemoglobin with reducing agents, such as ascorbate and cysteine reaches equilibrium when there are still considerable amounts of methemoglobin present in the solution.