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In diabetic patients, chronic hyperglycemia leads to non‐enz…

In diabetic patients, chronic hyperglycemia leads to non‐enzymatic glycation of hemoglobin, resulting in increased levels of glycated hemoglobin (HbA1c). This glycation process modifies amino acid residues on the hemoglobin molecule and can alter its quaternary structure. One important consequence is the potential impairment of binding of 2,3‐bisphosphoglycerate (2,3‐BPG), a key allosteric effector that normally binds to deoxyhemoglobin to stabilize the T (tense) state and promote oxygen release to tissues. When glycation reduces 2,3‐BPG binding, hemoglobin’s oxygen dissociation curve shifts to the left, meaning that oxygen binds more tightly. Although arterial oxygen saturation may remain normal, the increased oxygen affinity hampers oxygen release at the tissue level, contributing to tissue hypoxia and impaired wound healing—common complications in diabetes. This altered oxygen delivery mechanism, together with the accumulation of advanced glycation end-products (AGEs), plays a critical role in the pathophysiology of diabetic complications. Which of the following best explains the mechanism by which chronic hyperglycemia in diabetic patients leads to altered oxygen affinity of hemoglobin?  

In myoglobin, the heme group acts as a strong chromophore. I…

In myoglobin, the heme group acts as a strong chromophore. In its deoxy form (ferrous, Fe²⁺ without bound oxygen), it displays a prominent Soret band at 429 nm. Upon oxygen binding, this Soret band shifts to 414 nm, and the color observed by the eye changes from purplish (deoxymyoglobin) to red (oxymyoglobin). Which of the following best explains the molecular basis for this hypsochromic (blue) shift in the Soret band upon oxygen binding?