ESI Investigation of Non-Covalent Complexes between Phosphorylated Daidzein Derivatives and Insulin

Abstract

Since the end of the last century, ESI-MS has begun to be used to reveal the existence of non-covalent complexes, providing important stoichiometric information. Many researchers have reported the use of ESI-MS to determine dissociation constants of such complexes. Gas phase dissociation constants measured in this way have been found to correlate well with those measured by solution based techniques. ¹ , ² In this article, ESI results show that all the phosphorylated daidzein derivatives can form non-covalent complexes with the protein insulin, while non-covalent complexes were not detected in solutions of unphosphorylated daidzein and insulin. The relative affinity of each non-covalent complex was obtained according to its different decomposition orifice voltage. Compound e has the highest disappearing orifice voltage and therefore the strongest binding affinity. The relative stability of the non-covalent complexes was closely associated with the length of the hydrophobic chain.

Keywords:

• Daidzein
• ESI-MS
• insulin
• non-covalent complex
• phosphorylation

Acknowledgments

The authors thank the National Natural Science Foundation of China (No. 20472076 and 20175026) and Henan Academic Foundation of Science and Technology for their financial support.