Faster heme loss from hemoglobin E than HbS, in acidic pH: Effect of aminophospholipids

Journal of biosciences

Mousumi Banerjee²  Mohini Lahiry¹  Dipankar Bhattacharya³  Malini Pramanik¹  Samita Basu²  Abhjit Chakrabarti2 3¹ 

[1] Centre for Advanced Research & Education, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064, India$$;Chemical Science Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064, India$$;Structural Genomics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700 064, India$$

关键词: Aminophospholipids;    fluorescence;    Hb variant;    kinetics of heme loss;    Soret absorption;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

We report studies on loss of heme at or below pH 3.0 from two clinically important hemoglobin variants, HbE and HbS, in the presence and absence of phopholipid membranes. The kinetics of heme loss has been studied at pH 3.0 to simulate the same at a faster rate than at physiological pH, for spectroscopic investigation. Results obtained from the study clearly establish the probable fate of the lost heme to partition into the phospholipid bilayer independent of the pH range. This is also of particular importance to membranes containing the aminophospholipid and cholesterol which are predominantly localized in the inner leaflet of erythrocytes. Absorption measurements indicated such loss of heme when the Soret peak at 415 nm blue-shifted to 380 nm at pH 3.0. The extent of this blue shift decreased from 35 nm to ∼15 nm in the presence of small unilammelar vesicles of both dimyristoyl- and dioleoyl-based phosphatidylcholine and phosphatidylethanolamine, indicating partitioning of the released heme in the membrane bilayer. The kinetics of heme loss was faster from HbE than HbA and HbS, obeying first-order reaction kinetics. Released heme could be involved in the premature destruction of erythrocytes in hemoglobin disorders.

【 授权许可】

Unknown