Nitrile group as infrared probe for the characterization of the conformation of bovine serum albumin solubilized in reverse micelles

作者：Xue, Luyan; Zou, Feixue; Zhao, Yin; Huang, Xirong^*; Qu, Yinbo

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2012, 97: 858-863.

DOI：10.1016/j.saa.2012.07.076

• Nitrile group
• Infrared spectroscopy
• Reverse micelle
• Protein conformation

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 C N 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.

• 出版日期2012-11
• 单位微生物技术国家重点实验室; 山东大学