Extension arm facilitated pegylation of αα-hemoglobin with modifications targeted exclusively to amino groups: Functional and structural advantages of free cys-93(β) in the PEG-Hb adduct

Dongxia Li, Tao Hu, Belur N. Manjula, Seetharama A. Acharya

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Cys-93(β) of hemoglobin (Hb) was reversibly protected as a mixed disulfide with thiopyridine during extension arm facilitated (EAF) PEGylation and its influence on the structural and functional properties of the EAF-PEGHb has been investigated. Avoiding PEGylation of Cys-93(β) in the EAF-PEG-Hb lowers the level of perturbation of heme pocket, α1β2 interface, autoxidation, heme loss, and the O2 affinity, as compared to the EAF-PEG-Hb with PEGylation of Cys-93(β).The structural and functional advantages of reversible protection of Cys-93(β) during EAF PEGylation of oxy-Hb has been compared with Euro PEG-Hb generated by EAF PEGylation of deoxy Hb where Cys-93(β) is free in the final product. The αα-fumaryl cross-linking and EAF PEGylation targeted exclusively to Lys residues has been combined together for generation of second-generation EAF-PEG-Hb with lower oxygen affinity. The PEG chains engineered on Lys as well as PEGylation of Cys-93(β) independently contribute to the stabilization of oxy conformation of Hb and hence increase the oxygen affinity of Hb. However, oxygen affinity of the EAF-PEG-αα-Hb is more sensitive to the presence of PEGylation on Cys-93(β) than that of the EAF-PEG-Hb. The present modified EAF PEGylation platform is expected to facilitate the design of novel versions of the EAF-PEG-Hbs that can now integrate the advantages of avoiding PEGylation of Cys-93(β).

Original languageEnglish (US)
Pages (from-to)2062-2070
Number of pages9
JournalBioconjugate Chemistry
Issue number11
StatePublished - Nov 18 2009


ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biomedical Engineering
  • Pharmacology
  • Pharmaceutical Science
  • Organic Chemistry

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