The effects of cyclodextrins on the thermal denaturation and renaturation processes of bovine pancreatic ribonuclease A in an aqueous solution studied by circular dichroism and fluorescence spectroscopy
Keisuke Yoshikiyo, Ritsuko Takeshita, Tatsuyuki Yamamoto, Tetsuya Takahashi, Yoshihisa Matsui
Journal of Molecular Structure
Circular dichroism and fluorescence spectroscopic measurements showed that the thermal denaturation and renaturation processes of bovine pancreatic ribonuclease A (RNase A) in an aqueous solution at pH 7.0 are greatly affected by the addition of glucosyl-β-cyclodextrin (G1-β-CD). The addition of G1-β-CD lowered the thermal stability of RNase A to occur an irreversible denaturation of RNase A in the aqueous solution. The α- and γ-cyclodextrin gave less effect on the lowering of thermal stability. The ellipticity at 220 nm of the thermally denatured RNase A scarcely recovered with the re-cooling process with the addition of G1-β-CD. The temperature dependency of the fluorescence intensity at 309 nm arising from six tyrosine residues of RNase A was significantly affected by the addition of G1-β-CD. The effect of the addition of CDs was larger in the order of G1-β-CD > γ-CD > α-CD.
Circular dichroism, Protein denaturation, Thermal stability, Secondary structure, Biochemistry