Irreversible unfolding of myoglobin in an aqueous solution by supercritical carbon dioxide.
The conformational changes in myoglobin, treated by microbubbling of supercritical carbon dioxide (SC-CO(2)), were investigated by measuring the circular dichroism spectra in the ultraviolet range and compared with those in other proteins (ovoalbumin, bovine serum albumin, and beta-lactoglobulin). Irreversible unfoldings were observed after the microbubbling of SC-CO(2) at 35 degrees C and 30 MPa for 30 min. The degree of unfolding depended on the number of intramolecular S-S bonds. alpha-Helix contents of myoglobin decreased with increasing density of SC-CO(2). Unfoldings of myoglobin induced by heating, pH-lowering, and the addition of a denaturant were reversible. The irreversible unfolding of myoglobin was also observed by the bubbling of gaseous CO(2) under atmospheric pressure, but heating was required.
Ishikawa
H
H
Laboratory of Food Biotechnology, Department of Bioscience and Biotechnology, Division of Bioresource and Bioenviromental Science, Graduate School of Kyushu University, Fukuoka 812-8581, Japan. ishikawa@agr.kyushu-u.ac.jp
Shimoda
M
M
Yonekura
A
A
Mishima
K
K
Matsumoto
K
K
Osajima
Y
Y
D000818:Animals; D002245:Carbon Dioxide / Q000737:chemistry*; D006736:Horses; D009211:Myoglobin / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D012996:Solutions
D009211:Myoglobin; D012996:Solutions; D002245:Carbon Dioxide