Determination of accurate protein monoisotopic mass with the most abundant mass measurable using high-resolution mass spectrometry

作者：Chen Ya Fen; Chang C Allen; Lin Yu Hsuan; Tsay Yeou Guang^*

来源：Analytical Biochemistry, 2013, 440(1): 108-113.

DOI：10.1016/j.ab.2013.05.018

• Monoisotopic mass
• Most abundant mass
• High-resolution mass spectrometry

While recent developments in mass spectrometry enable direct evaluation of monoisotopic masses (M-mi) of smaller compounds, protein M-mi is mostly determined based on its relationship to average mass (M-av). Here, we propose an alternative approach to determining protein M-mi based on its correlation with the most abundant mass (M-ma) measurable using high-resolution mass spectrometry. To test this supposition, we first empirically calculated M-mi and M-ma of 6158 Escherichia coli proteins, which helped serendipitously uncover a linear correlation between these two protein masses. With the relationship characterized, liquid chromatography-mass spectrometry was employed to measure M-ma of protein samples in its ion cluster with the highest signal in the mass spectrum. Generally, our method produces a short series of likely M-mi in 1-Da steps, and the probability of each likely M-mi is assigned statistically. It is remarkable that the mass error of this M-mi is as miniscule as a few parts per million, indicating that our method is capable of determining protein M-mi with high accuracy. Benefitting from the outstanding performance of modern mass spectrometry, our approach is a significant improvement over others and should be of great utility in the rapid assessment of protein primary structures.

• 出版日期2013-9-1