Spectroscopic study on acid-induced unfolding and refolding of apo-neuroglobin.
pH-induced unfolding and refolding of apo-neuroglobin (apo-Ngb) were investigated by UV, fluorescence, circular dichroism (CD) spectra and light scattering measurements. Results revealed that apo-Ngb became partially unfolded at around pH 5.0, with evidences from a red shift in the fluorescence spectra, a decrease in the far-UV CD and a sharp peak in the light scattering intensity. Further lowering of the pH reversed these effects, suggesting that apo-Ngb folds back to a compact state. At pH 2.0, the apo-Ngb forms a folding intermediate known as molten globule (MG), which is possessed of native-like secondary structure and almost complete loss of tertiary structure. Based on these results, the acid-induced denaturation pathway of apo-Ngb can be illustrated from the native state (N), via a partially unfolded state (U(A)) to the molten globule state (MG).
School of Chemistry and Chemical Engineering, Liaocheng University, No. 1, Hunan Road, Liaocheng 252059, Shandong Province, PR China.
Jianshuai
J
Mu
Lianzhi
L
Li
Yujing
Y
Guo
Zhanglei
Z
Qiu
Xiangshi
X
Tan
D000817:Anilino Naphthalenesulfonates / Q000737:chemistry; D001059:Apoproteins / Q000737:chemistry* / Q000378:metabolism*; D002942:Circular Dichroism; D005914:Globins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008027:Light; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D000078787:Neuroglobin; D017510:Protein Folding; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet
C515594:8-anilino-1-naphthalenesulfonic acid; D000817:Anilino Naphthalenesulfonates; D001059:Apoproteins; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D005914:Globins