Oxidative stability of avian hemoglobin components A and D and their differential capabilities to handle oxidative insult

Tuesday, October 25, 2011 — Poster Session II
Noon – 2:00 p.m.	Natcher Conference Center	FDA/CBER	OXIDSTRESS-9

Authors

• CP Pereira
• E Karnaukhova
• DJ Schaer
• PW Buehler

Abstract

Introduction: Hb released into the circulation or tissue compartments may lead to oxidation of heme iron and globin. Avian Hbs have identical b chains but differ in the sequence of the a subunits and are termed A (a2Ab2) and D (a2Db2) and several reports highlight the oxygen binding of Hb D. Interestingly, a2D is a prominent embryonic component in certain mammals. The present work was designed to understand differences in oxidative stability of Hb A and D to begin to understand their contribution to managing Hb induced oxidative stress. Methods: Components A and D from Leghorn chicken RBCs were isolated. Heme iron oxidation and stability to H2O2 was studied by spectral analysis, nitrone-antibody free radical spin trapping was evaluated by immunoblotting and amino acid oxidations were quantified by mass spectrometry. Additionally, structural changes following H2O2 reactivity were monitored by circular dichroism. Results and conclusions: Hb D was more resistant to heme iron oxidation, free radical generation and globin chain oxidation than Hb A. Protein sequence analysis revealed a2A contains a cysteine (aACys131) not present in a2D. these data begin to explain the differential oxidative stability of these components. However, questions remain regarding their functional role in oxidative stress.

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