Chaperone-like effects of a scFv antibody on the folding of human muscle creatine kinase

Abstract

Molecular chaperones play an essential role in assisting the folding of a myriad of nascent peptides to form different biologically active proteins. Therefore, their low substrate specificity is important for the functions of these housekeeping proteins. However, discovering chaperones which assist the folding of a particular protein can shed new light on the folding pathway of the protein, offering an interesting approach for developing specific therapeutic agents to treat protein-misfolding diseases. Screening of antibodies with chaperone-like function represents a novel strategy to meet the challenges. In this study, some single-chain variable fragment (scFv) antibodies were selected from a high-capacity phage antibody library using human muscle creatine kinase (HCK) as antigen. A scFv antibody (scFv A4) was determined to inhibit aggregation and favor recovery of the native conformation of HCK during its refolding. This antibody also increased the stability of HCK during its heat-induced unfolding process. Our findings demonstrate that scFv A4 has dual-chaperone-like activities: assisting in correct protein folding as well as protecting the native protein from unfolding. A molecular mechanism by which scFv A4 exhibits chaperone-like effects on HCK was proposed. This study demonstrates that phage antibody libraries can lead to chaperone-like proteins, and the specificity of the resulting antibody toward its antigen could provide new molecular details regarding how the chaperone interacts with the protein's unfolding and folding pathways.