Having just examined the weak binders-FKBP systems-in the previous section, we shall show the results of a strong binder system-the streptavidin-biotin system-whose binding affinity is on the order of pM. The dissociation rates of the variants have been reported using various experimental techniques, with values ranging from 10 )3 to 10 )4 s )* 46,53-55 . The dissociation rate of the engineered streptavidin-biotin complex addressed here was ~10 )3 s )* 46 . In this section, we attempt to estimate the dissociation rate without a constant force and determine if it matches the experimental value. Similar to the systems we discussed, we calculated the dissociation time 𝜏(𝐹) for each strength of a constant force (200, 250, 300, and 400 pN), estimating the dissociation time without a constant force using Bell's and DHS models (Figure and Table ). The dissociation time decreased as the strength of the force increased. Bell's model provided the low bound of the dissociation time without a constant force (blue line in Figure ) and underestimated the dissociation time considerably smaller than the DHS model (orange line in Figure ) because of the inability to account for nonlinear dependency. We compared the experimental value of the dissociation time. The DHS model predicted that 𝜏 ' = 6.47 × 10 5 s, which corresponds to 𝑘 +,, = 1.55 × 10 )3 s )* . This corresponded with the experimental value 𝑘 +,, 067 = 1.05 × 10 )3 s )* 46 . As indicated by Table in a review , the error factors of the dissociation rate estimated by state-of-the-art computational methods ranged from 2-to 100-fold. Thus, our dissociation rate calculation showed an accuracy comparable to that of earlier studies.