Nitrile group as infrared probe for the characterization of the conformation of bovine serum albumin solubilized in reverse micelles.
Infrared spectroscopy is a powerful technique for structure characterization. For a protein hosted in a reversed micellar medium, the spectral features of the protein are always interfered by the IR absorption bands of the medium in addition to the congestion in their IR spectra. Fortunately, there is a transparent window in the 2500-2200 cm(-1) region. Incorporation of a vibrational probe with IR absorption frequencies in this region into proteins represents a promising strategy for the study of the conformation of a protein in a reverse micelle. In the present work, we incorporated 4-cyanobenzyl group (CN) into bovine serum albumin (BSA) via cysteine alkylation reactions under mild conditions. Circular dichroism spectroscopy showed that the CN modified BSA (CNBSA) could retain its conformation. When CNBSA was hosted in AOT reverse micelle, it was found that the nitrile group on BSA was sensitive to the conformational change of BSA induced by urea as an additive in the reverse micelle. The peak splitting of nitrile group was also observed when the size of AOT reverse micelle and the concentration of an electrolyte were varied. Obviously, the shift of the IR absorption peak and/or peak splitting of nitrile group on BSA are correlated with the change of BSA conformation in AOT reverse micelle. So we conclude that the nitrile infrared probe can be used to study protein conformation in a reverse micelle.
Key Laboratory of Colloid & Interface Chemistry of the Education Ministry of China, Shandong University, Jinan 250100, PR China.
Luyan
L
Xue
Feixue
F
Zou
Yin
Y
Zhao
Xirong
X
Huang
Yinbo
Y
Qu
D000818:Animals; D002417:Cattle; D002942:Circular Dichroism; D008823:Micelles; D015335:Molecular Probes / Q000737:chemistry*; D009570:Nitriles / Q000737:chemistry*; D017433:Protein Structure, Secondary; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012995:Solubility; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D014466:Ultraviolet Rays
D008823:Micelles; D015335:Molecular Probes; D009570:Nitriles; D012710:Serum Albumin, Bovine