No abstract

A new strategy is reported for creating protein-based nanomaterials by genetically fusing large polypeptides to monomeric streptavidin and exploiting the propensity of streptavidin monomers(SM) to self-assemble into stable tetramers. We have characterized the mechanical properties of streptavidin-linked structures and measured, for the first time, the mechanical strength of streptavidin tetramers themselves. Using streptavidin tetramers as molecular hubs offers a unique opportunity to create a variety of well-defined, self-assembled protein-based (nano) materials with unusual mechanical properties

Staphylococcal nuclease (SNase) catalyzes the hydrolysis of DNA and RNA in a calcium-dependent fashion. We used AFM-based single-molecule force spectroscopy to investigate the mechanical stability of SNase alone and in its complex with an SNase inhibitor, deoxythymidine 3',5'-bisphosphate. We found that the enzyme unfolds in an all-or-none fashion at ∼26 pN. Upon binding to the inhibitor, the mechanical unfolding forces of the enzyme-inhibitor complex increase to ∼50 pN. This inhibitor-induced increase in the mechanical stability of the enzyme is consistent with the increased thermodynamical stability of the complex over that of SNase. Because of its strong mechanical response to inhibitor binding, SNase, a model protein folding system, offers a unique opportunity for studying the relationship between enzyme mechanics and catalysis.

No abstract