ABSTRACT
The physical environments leading to C9 polymerization are summarized in Table 3. It appears that monomeric C9 has a meta-stable conformation. Agents which destabilize this labile conformation lead to restricted unfolding of C9. Chaotropic agents at low concentration can cause a perturbation of C9's tertiary structure. Detergents may have a similar effect. They may act in addition by shifting the equilibrium of monomeric to unfolded, amphiphilic form of C9, since they can interact with the hydrophobic domain(s) of the latter structure. Enzymes may destabilize C9 by increasing the flexibility of monomeric C9, thereby facil-
Table 2 INFLUENCE OF METAL IONS ON C9 POLYMERIZATION
itating the unfolding. The decrease in ionic strength favors the amphiphilic form of C9 due to the lowering of the dielectric constant and facilitating C9-C9 contact. In contrast, high ionic strength conditions stabilize the monomeric nature of C9. It is proposed that the unfolded C9 exhibits a high affinity for monomeric C9 and can serve as nucleus for further C9 polymerization (see detailed discussion of mechanism in paragraph 4).
