Human serum albumin incorporating Tetrakis(o-pivalamido) phenylporphinatoiron(II) derivative as a totally synthetic O2-carrying hemoprotein.
2-[8-{N-(2-Methylimidazolyl)}octanoyloxymethyl]-5,10,15, 20-tetrakis(o-pivalamido)phenylporphinatoiron(II)s (FePs) were incorporated into hydrophobic cavities of recombinant human serum albumin (rHSA), providing a totally synthetic O(2)-carrying hemoprotein (rHSA-FeP). An rHSA host absorbs maximally eight FeP molecules. Solution properties of the obtained albumin hybrid [[rHSA] = 5 wt %; FeP/HSA = 1-8 (mol/mol)] are almost identical to those of the rHSA itself; the specific gravity is 1.013 and the viscosity is 1.1 cP. Circular dichroism spectroscopy and isoelectric focusing measurement revealed that the second-order structure and surface charge distribution of rHSA were always constant independent of the binding numbers of FeP. Hydrophobic interaction is probably a major molecular force of the incorporation of this synthetic heme. rHSA-FeP can bind and release dioxygen reversibly under physiological conditions (in aqueous media, pH 7.3, 37 degrees C) like hemoglobin and myoglobin. Its O(2)-coordination structure was evaluated by resonance Raman spectroscopy. The O(2) rebinding after the laser flash photolysis showed three-phases decay, which were analyzed by triple-exponential kinetics. The O(2)-binding affinity and O(2)-association and -dissociation rate constants of rHSA-FeP satisfy the initial clinical requirements for O(2) infusion as a red cell substitute.
Tsuchida
E
E
Department of Polymer Chemistry, Advanced Research Institute for Science & Engineering, Waseda University Tokyo 169-8555, Japan. eishun@mn.waseda.ac.jp
Komatsu
T
T
Matsukawa
Y
Y
Hamamatsu
K
K
Wu
J
J
D001802:Blood Substitutes / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D006420:Hemeproteins / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D007526:Isoelectric Point; D007700:Kinetics; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism; D012709:Serum Albumin / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism*; D000075462:Serum Albumin, Human; D012996:Solutions; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman
D001802:Blood Substitutes; D006420:Hemeproteins; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D012709:Serum Albumin; D012996:Solutions; C400056:rHSA-FeP protein, human; D010100:Oxygen; D000075462:Serum Albumin, Human