Hemoglobin(βC93A)–Albumin Cluster: Mutation of Cysteine-β93 to Alanine Allows Moderate Reduction of O₂ Affinity by Inositol Hexaphosphate

Graphical Abstract

Accepting substitutes: A core–shell protein cluster comprising a recombinant human hemoglobin variant (rHb(βC93A)) at the center and human serum albumin (HSA) at the exterior is synthesized as an artificial O₂ carrier to act as a substitute for red blood cells. The rHb(βC93A)-HSA₃ cluster shows controllable O₂ affinity by complexation of the allosteric effector inositol hexaphosphate.

Abstract

Covalent wrapping of recombinant human hemoglobin (Cys-β93→Ala) variant rHb(βC93A) by human serum albumin (HSA) yielded the rHb(βC93A)-HSA₃ cluster as an artificial O₂ carrier as a red blood cell substitute. Complexation of inositol hexaphosphate to the central rHb(βC93A) core reduced the O₂ affinity moderately, in much the same way as that of naked hemoglobin. This reduction might be attributable to the inert, small Ala-β93 residue, which cannot be reacted with the bulky maleimide crosslinker.