Induced thermostability of poly(ethylene oxide)-modified hemoglobin in glycols.
The thermostability and redox activity of poly(ethylene oxide) (PEO)-modified human hemoglobin in PEO200 (PEO containing KCl, average MW of 200, < 0.3% H2O) were investigated by UV-vis spectroscopy, by circular dichroism spectroscopy, and by cyclic voltammetry. Using PEO oligomers as a solvent, PEO-modified hemoglobin was reduced and oxidized at an indium tin oxide glass electrode in the temperature range of -10 to 120 degrees C. The thermostability of PEO-modified hemoglobin was affected by the molecular weight of the solvent PEO. In lower-molecular weight glycols (MW of < 150), PEO-modified hemoglobin was denatured within a few minutes at 80 degrees C. On the other hand, the absorbance at the Soret band for PEO-modified hemoglobin was unchanged for 2 h at 80 degrees C in PEO200. A decrease in the water content of solvent PEO200 also improved the thermostability of PEO-modified hemoglobin. Improvement in the thermostability was attributed to physicochemical characteristics such as the relatively low molecular motion of PEO oligomers used as a solvent.
Kawahara
N Y
NY
Department of Biotechnology, Tokyo University of Agriculture & Technology, Japan.
Ohno
H
H
D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D004355:Drug Stability; D004563:Electrochemistry; D006018:Glycols / Q000737:chemistry; D006454:Hemoglobins / Q000737:chemistry*; D006358:Hot Temperature; D006801:Humans; D008970:Molecular Weight; D011092:Polyethylene Glycols / Q000737:chemistry*; D012997:Solvents; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
D006018:Glycols; D006454:Hemoglobins; D012997:Solvents; D014867:Water; D011092:Polyethylene Glycols