bi026046h_si_002.pdf (30.92 kB)
Myoglobin Scavenges Peroxynitrite without Being Significantly Nitrated
journal contribution
posted on 2002-10-19, 00:00 authored by Susanna Herold, Kalinga Shivashankar, Martin MehlWe have analyzed in detail hemoglobin (Hb) and myoglobin (Mb) after treatment of different
forms of these proteins with variable amounts of peroxynitrite. HPLC analyses of the peroxynitrite-treated
proteins subjected either to acid hydrolysis or Pronase digestion showed that only very low quantities of
3-nitrotyrosine are formed when equivalent amounts of peroxynitrite are allowed to react with the oxy
form of these proteins. Comparable amounts of nitrated amino acids are formed when metMb and metHb
are treated with peroxynitrite under analogous conditions, but significantly larger yields are observed
with apoMb and metMbCN. Interestingly, in addition we found that also the tryptophan residues of Mb
and Hb are nitrated to a low but detectable extent. Taken together, our data suggest that the heme center
of Mb may act as an efficient scavenger of peroxynitrite, protecting the globin from nitration. As
peroxynitrite can irreversibly inhibit cytochrome c oxidase, oxyMb may utilize an additional important
pathway to maintain mitochondrial respiration, that is, rapidly react with peroxynitrite and thus prevent
nitration of other cellular components.