Fig. 2.

Minimal mechanism for nucleated growth of amyloid in bulk phase corresponding to Eq. 3. Nucleation is considered to occur via a bimolecular addition reaction (nucleus size n = 2) governed by a second-order-nucleation rate constant, $k_{n{\left(A\right)}_B}$. Fiber growth is able to occur by monomer addition and fiber end-to-end joining, respectively regulated by second-order rate constants, $k_{g{\left(A\right)}_B}$, and $k_{j{\left(A\right)}_B}$. Fiber shrinkage is able to occur by breakage (scission) of monomer from the fiber end or via fracture at some internal position within the fiber. The rate of fracture at a particular site is considered to be governed by a first-order scission rate constant, $k_{S°{\left(A\right)}_B}$, with this site-value considered to be independent of position (as a first approximation). (Translated and reprinted with full permission from Hirota and Hall (2019), CMC Publishing Corporation)