Functional aspects of hemoglobin evolution in the mammals

Area of Science:

• Biochemistry
• Evolutionary Biology
• Physiology

Background:

• 2,3-Diphosphoglycerate (DPG) is a key regulator of hemoglobin-oxygen affinity in mammalian red blood cells.
• DPG levels and their impact on oxygen transport vary across mammalian taxa.
• Anomalous DPG levels have been observed in certain mammalian groups.

Purpose of the Study:

• To investigate the role of 2,3-Diphosphoglycerate (DPG) in hemoglobin-oxygen affinity in diverse mammalian species.
• To identify and characterize mammalian groups with unusual DPG concentrations and their effects on hemoglobin function.
• To explore the evolutionary adaptations in hemoglobin structure and function in response to altered DPG levels.

Main Methods:

• Comparative analysis of red blood cell 2,3-Diphosphoglycerate (DPG) levels across a taxonomically diverse mammalian set.
• Assay of red cell lysates to determine the DPG effect on hemoglobin oxygen affinity.
• Examination of hemoglobin structure and function in relation to DPG levels.

Main Results:

• Mammals from the superfamilies Bovoidea (Artiodactyla) and Feloidea (Carnivora) exhibited very low or unmeasurable DPG quantities.
• Red cell lysates from these anomalous groups showed minimal DPG effect on oxygen affinity.
• Compensatory alterations in hemoglobin structure and function were observed, reducing native oxygen affinity in these taxa.

Conclusions:

• The Bovoidea and Feloidea superfamilies represent anomalous groups regarding DPG levels and hemoglobin-oxygen affinity regulation.
• Convergent evolution has led to similar functional adaptations in hemoglobin across these distinct mammalian lineages despite low DPG.
• Hemoglobin's reduced oxygen affinity in these groups effectively compensates for the lack of DPG, ensuring efficient oxygen delivery.