Using single-molecule force spectroscopy of the 27th domain (I27) of human cardiac muscle protein titin, we show that the average unfolding force of the protein decreases with increase in the ionic radii of the surrounding anions in the order Cl- > Br- > NO3- > I- > SO42- ≈ ClO4-, indicating an inverse correlation between anion size and the mechanical stability of I27. 
single-molecule force spectroscopy
Using single-molecule force spectroscopy of the 27th domain (I27) of human cardiac muscle protein titin, we show that the average unfolding force of the protein decreases with increase in the ionic radii of the surrounding anions in the order Cl- > Br- > NO3- > I- > SO42- ≈ ClO4-, indicating an inverse correlation between anion size and the mechanical stability of I27. 
the 27th domain (I27) of human cardiac muscle protein titin