Surface Modification of Reconstituted Hemoglobins Containing SOD-Active Metalloporphyrins

Abstract

Reconstituted hemoglobins modified with polyethylene glycol (PEG) containing iron(III) and manganese(III) complexes of meso-tetra(N-methylpridinium-x-yl)porphyrin ([MTxMePyP]-Hb-PEG, M = Fe and Mn, x = 2 and 4) were found to serve as excellent superoxide dismutase (SOD) mimics under physiological conditions. IC₅₀ was 2.3 μ M and the pseudo-first order rate constant was 2.2 × 10⁶ M^-1s^-1 for reaction of MnT2MePyP-Hb-PEG with a superoxide anion radical as detemined by conventional cytochrome c assay and stopped flow analysis, respectively. Stability toward H₂O₂ by surface modification of reconstituted hemoglobins with PEG chains helped prevent aggregation with other proteins such as albumin.