Properties of and oxygen binding by albumin-tetraphenylporphyrinatoiron(II) derivative complexes

Eishun Tsuchida, Katsutoshi Ando, Hiromitsu Maejima, Noriyuki Kawai, Teruyuki Komatsu, Shinji Takeoka, Hiroyuki Nishide

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

A hydrophobic tetraphenylporphyrinatoiron(II) derivative bearing a covalently bound axial imidazole [Fe(II)P] was efficiently and noncovalently bound into human serum albumin (HSA) up to an average of eight Fe(II)P molecules per HSA molecule. The aqueous solutions of the HSA-Fe(II)P complex provided a reversible and relatively stable oxygen adduct under physiological conditions (pH 7.4 and 37 °C). The half-life of the oxygen adduct (τ( 1/4 )) was 1 h at 37 °C in an air atmosphere. With Fe(II)-TpivPP (the so-called 'picket-fence heme') having no axial base, an oxygenated HSA-Fe(II)TpivPP complex was obtained using a 20-fold molar excess of 1,2-dimethylimidazole, but the τ( 1/4 ) was very short (ca. 10 min at 37 °C). The oxygen affinity [P( 1/4 )(O2)] and oxygen transporting efficiency (OTE) of HSA-Fe(II)P at 37 °C were 30 Torr and 22%, respectively. Furthermore, the oxygen-binding and dissociation rate constants (k(on) and ko(off)) are extremely high in comparison with those of hemoglobin. The HSA molecule binding eight Fe(II)P molecules can transport about 3.4 mL/dL of oxygen under physiological conditions, corresponding to about 60 % of the oxygen transporting amount of human blood.

Original languageEnglish
Pages (from-to)534-538
Number of pages5
JournalBioconjugate Chemistry
Volume8
Issue number4
DOIs
Publication statusPublished - 1997 Jul 1

ASJC Scopus subject areas

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

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