L-Histidine enhances stability of hemoglobin concentrates by coordinating with free iron

The objective of this investigation was to evaluate the effects of L-histidine on the stability of porcine hemoglobin concentrates during storage. The results indicated that the addition of L-histidine increased the oxyhemoglobin content and a* values but decreased the methemoglobin content and free iron content (P < 0.05) during storage. The addition of iron cation decreased both the oxyhemoglobin content and a* values but increased both the methemoglobin content and free iron concentration (P < 0.05). CD spectra revealed that the free iron content induced the transformation of the hemoglobin secondary structure from an alpha-helix (close structure) to a beta-pleated, beta-turn, and random coil arrangement (loose structure), while L-histidine weakened this behavior of the free iron. Infrared spectra demonstrated that the L-histidine coordinated with the free iron (Fe2+ or Fe3+) to give the corresponding complex at 25 degrees C and pH 7.3. Therefore, L-histidine enhanced the stability of hemoglobin concentrates by coordinating with free iron. (C) 2014 Elsevier Ltd. All rights reserved.