Quantitation of nucleoprotein complexes by UV absorbance and Bradford assay

Jiang Chen; Hao Luo; Mei Tao; Zhongchuan Liu; Ganggang Wang

doi:10.52601/bpr.2021.210028

Quantitation of nucleoprotein complexes by UV absorbance and Bradford assay

Biophys Rep. 2021 Dec 31;7(6):429-436. doi: 10.52601/bpr.2021.210028.

Authors

Jiang Chen^{1

2

3}, Hao Luo^{1

3}, Mei Tao¹, Zhongchuan Liu¹, Ganggang Wang¹

Affiliations

¹ Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences; Key Laboratory of Environmental Microbiology of Sichuan Province, Chengdu 610041, China.
² College of Life Sciences, Sichuan University, Chengdu 610064, China.
³ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Despite the importance of studying nucleoprotein complexes, no appropriate method for quantifying them is available. Here, a UV absorbance method using the formula "C_mg/mL = 1.55A₂₈₀ - 0.76A₂₆₀" were applied to quantify nucleoprotein complexes. After modification using two paired A₂₆₀ and A₂₈₀ values, the UV-derived formula-based method could accurately quantify proteins in nucleoprotein complexes. Otherwise, by taking the target protein as a standard, the Bradford assay can accurately quantify proteins in nucleoprotein complexes without interference by nucleic acids. The above methods were successfully applied to measure the concentration of MtuP49-CTG complexes of Mycobacterium tuberculosis. In conclusion, both the Bradford assay and the UV-derived formula-based method were appropriate for quantifying proteins in nucleoprotein complexes, which may make contributions to explore the interactions between proteins and nucleic acids at the molecular level.

Keywords: Bradford assay; Nucleoprotein complex; Quantitation; UV-derived formula-based method.