Streptavidin tetramerization and 2D crystallization: A mean-field approach

A mean-field theoretical approach is applied to streptavidin tetramerization and two-dimensional (2D) crystallization. This theory includes, in particular, solvent-residue interactions following the inhomogeneous Flory-Huggins model for polymers. It also takes into account residue-residue interactions by using tabulated pair interaction parameters. This theory allows one to explicitly calculate the entropy of the inhomogeneous system. We show that hydrophobic interactions are responsible for the stability of tetramerization. Within the present theory, the equilibrium distance between the two dimers is the same as that determined experimentally. The free energy of tetramerization (i.e. dissociation of the two dimers) is 50 kBT. Unlike tetramerization, hydrophobic interactions alone are not sufficient to stabilize the 2D crystal C222, but solvent-mediated residue-residue interactions give the most important contribution.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Stability of ordered phases in weakly segregated diblock copolymer systems

Stability of ordered phases in diblock copolymer melts is studied using a theory of anisotropic fluctuations, which bears a useful similarity with energy band theory in solids. We calculated stability lines of all ordered phases and found the hexagonally perforated lamellar phase to be unstable around the lamellar-cylindrical (LC) phase boundaries. We used fluctuation analysis to obtain dynamical pathways between ordered phases and argue that the observed modulated layered states along LC boundary regions are due to infinitely degenerate fluctuation modes of the lamellar phase. © 1997 American Physical Society

Stability of ordered phases in diblock copolymer melts

The stability of the diblock copolymer ordered phases is investigated by means of a novel theory of anisotropic composition fluctuations. The analogy between a polymer chain in a periodic structure and an electron in a crystalline solid is exploited in the development of the theory. This theory allows the calculation of the spinodal lines, the most unstable modes, and the scattering functions of the ordered phases. The one-phase regions of the lamellar, cylindrical, and spherical phases are found to be within their corresponding stability regions. On the other hand, the hexagonally-perforated lamellar phase is unstable along the lamellar-cylindrical phase boundary. The most unstable fluctuation modes are readily identified and are used to infer the kinetic pathways of the order-order phase transitions. We speculate that the experimentally observed modulated and/or perforated layered states along the lamellar-cylindrical phase boundary are a consequence of the infinitely degenerate fluctuation modes of the lamellar phase. The scattering functions of all ordered phases are calculated. The stability of the double gyroid phase is also investigated

Screening for genetic mutations [1]

Scientific Correspondence: Rapid detection of single-base substitution by PNA-DNA hybridization in capillary electrophoresislink_to_subscribed_fulltex