Hemoglobin-dialdehyde dextran conjugates: improvement of their oxygen-binding properties with anionic groups

Area of Science:

• Biochemistry
• Polymer Chemistry
• Bioconjugation

Background:

• Hemoglobin (Hb) is crucial for oxygen transport.
• Dextran is a polysaccharide used in various biomedical applications.
• Modifying Hb with polymers can alter its oxygen-binding properties.

Purpose of the Study:

• To investigate the formation and properties of hemoglobin-dextran conjugates.
• To assess the impact of sulfated versus unsulfated dextran on conjugate characteristics.
• To understand how coupling conditions influence hemoglobin's oxygen affinity.

Main Methods:

• Conjugation of hemoglobin with oxidized dextran (sulfated and unsulfated).
• Characterization of conjugate molecular size and structure.
• Measurement of oxygen-binding affinity (P50) of the resulting conjugates.

Main Results:

• Sulfated dextran favors imine bond formation, leading to larger conjugates.
• Conjugation with unsulfated dextran and oxyhemoglobin increases oxygen affinity.
• Conjugation with deoxyhemoglobin or sulfated dextran decreases oxygen affinity, with sulfated dextran acting as a permanent effector.
• Evidence suggests linkage to the 2,3-diphosphoglycerate binding site.

Conclusions:

• The presence of sulfated groups on dextran significantly influences hemoglobin conjugation and oxygen-binding properties.
• Sulfated dextran acts as a potent, permanent macromolecular effector of hemoglobin.
• The oxygen affinity of hemoglobin-dextran conjugates can be modulated by the type of dextran and coupling conditions.