A simple methods for obtaining a multivalent protein with a variable number of binding sites and estimating its binding parameters

The study of natural and the design of artificial multivalent proteins is a promising field of molecular biology. Working with such proteins is much more difficult than with their monovalent analogues. In this paper, we show how using a ring of heptameric Sm-like protein as a scaffold, it is possible to create a multivalent protein with a different number of binding sites. This is an urgent task for the study of multivalent and multicenter protein-protein interactions. The method of analysis used in the work allows us to evaluate the stoichiometry and the dissociation constant of complexes of artificial chaperone with a non-native protein. It is shown that for reliable binding of non-native αLA, its interaction with several apical domains of GroEL is necessary. At the same time, the dissociation constant of such a complex does not significantly change with an increase in the number of binding domains in the oligomer. Up to 4 αLA molecules can be attached to the complete heptameric ring of apical domains. The proposed methods have a good cost-to-result ratio and can be applied to the study and design of other new proteins. ### Competing Interest Statement The authors have declared no competing interest.