Analysis of the interferences in quantitation of a site-specifically PEGylated exendin-4 analog by the Bradford method
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Published on: September 10, 2017
Xiaowei Qian1, Hongxia Dong1, Xiaojing Hu1
1Department of Biochemistry, China Pharmaceutical University, Nanjing 210009, China.
Abstract:
Protein modification has been found to affect the estimation of protein concentration in some of the traditional dye-based absorbance measurements. In this work, a distinct reduction in A595 was observed during the quantitation of a PEGylated exendin-4 analogue (Ex4C) by the Bradford method and the PEGylation process was found to interfere with the measurement. Lys(12), Arg(20), and Lys(27) were further proved to be the major amino acids that functioned as dye-binding sites. The shielding effect produced by the large polymer was demonstrated to depend on the length of PEG that was used for modification.
