Coordination of l-arginine and iron cation improves stability of hemoglobin concentrates

This work evaluated the effects of l-arginine on the stability of porcine hemoglobin concentrates during storage. The addition of l-arginine increased both the oxyhemoglobin content and a* values but decreased both 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 content (p < 0.05). CD spectra disclosed that the free iron induced the transformation of the hemoglobin secondary structure from an α-helix to a β-pleated, β-turn, and random-coil arrangement, while l-arginine hindered the behavior of the free iron. Infrared spectra revealed that the l-arginine coordinated with the free Fe2+ or Fe3+ to form the corresponding complex at 25 °C and pH 7.3. These results showed that l-arginine enhanced the stability of hemoglobin concentrates by coordinating with free iron.