Tris(3,5-dibromosalicyl) tricarballylate crosslinked hemoglobin: functional evaluation

Area of Science:

• Biochemistry
• Protein Chemistry
• Structural Biology

Background:

• Human hemoglobin A (HbA) is crucial for oxygen transport.
• Understanding HbA's structural dynamics is key to its function.
• Chemical crosslinking can probe protein stability and conformation.

Purpose of the Study:

• To investigate the effects of inter-subunit crosslinking on human hemoglobin A.
• To analyze changes in thermal stability, autoxidation rates, and oxygen binding properties.

Main Methods:

• Human hemoglobin A (oxy and deoxy forms) was crosslinked using tris(3,5-dibromosalicyl) tricarballylate.
• Thermal denaturation transition temperature (Tm) was measured.
• Autoxidation rate constants (kapp) were determined.
• Oxygen affinity and cooperativity were assessed.

Main Results:

• The major crosslinked species contained an inter-subunit crosslink.
• Crosslinked oxyhemoglobin Tm increased by 14.5°C; deoxyhemoglobin Tm increased by 13.0°C.
• Deoxy crosslinked hemoglobin showed a 34% increase in autoxidation rate.
• Crosslinked proteins exhibited higher oxygen affinity and lower cooperativity.

Conclusions:

• Inter-subunit crosslinking enhances hemoglobin stability.
• The crosslink induces a conformational shift towards the R state, favoring oxygen binding.
• Crosslinking modifies hemoglobin's functional properties, impacting oxygen transport efficiency.