AFMを用いた単一分子の動的力学測定

抄録

Polyproline forms a unique structure, called polyproline-IIhelix(PPII) in water. PPII is known to be a rigid molecule in spite of no hydrogen bonds between backbone atoms, and to play an important role in biological functions such as formation of collagen structure and in the cell-adhesion. In this study, we carried out single molecule force spectroscopy of polyproline with AFM(Atomic Force Microscope) and covalent immobilization of polyproline molecule on gold substrate to evaluate the rigidity of PPII at single molecule level. We found that the force-extension curve of polyproline shows a linear increase, which is unusual and not seen with others homo-polypeptide molecules. These results indicate that the high rigidity of polyproline II helix can be explained by “enthalpic”, not “entropic” driven elasticity.