Impact of Amino Acid Modifications on Hemoglobin Affinity for Oxygen

Very Hard Biochemistry Amino Acids And Proteins

Human hemoglobin is a tetrameric protein that comprises two alpha and two beta subunits. Each subunit binds one molecule of oxygen via a heme prosthetic group. This binding is affected by several factors, including pH, carbon dioxide concentration, and 2,3-bisphosphoglycerate (2,3-BPG) levels. An important aspect of hemoglobin's functionality is its allosteric regulation, which allows it to undergo conformational changes in response to substrate binding. Consider the implications of amino acid composition and modifications on hemoglobin's oxygen affinity. Which of the following modifications to the amino acid sequence of the beta subunits would most likely decrease hemoglobin's affinity for oxygen?

Substitution of a histidine residue with a valine residue.

Addition of an aspartic acid residue at the C-terminus of the beta subunit.

Introduction of a serine residue in place of a glutamic acid residue.

Removal of a proline residue from the heme binding pocket.

Hint

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