Crystalline structure interface steps

The structure of the interdomain interface in bovine yB- and PB2-crystallins is very similar in both proteins (1-2). In yB-crystallin the inter ce is formed by domains from the same molecule, while in the PB2-crystallin dimer the interface consist of residues from swapped amino- and caiboxy-terminal domains of two different molecules which associate to form a dimer. Domain swapping can be considered as a common step for the oligomerization of proteins and may play an important role in the evolution of oligomeric proteins (3-4). The importance of surface interactions in formation of intermolecular contacts in protein crystals is shown by comparative studies of various y-crystallins (5-6). These suggest that differences in surface interactions between the domains of P- and y-crystallin may be responsible for dimer formation by 3-crystallins. 

Figure 8 Schematic representation of the processes leading to birefringence (and turbidity) in a W/O microemulsion, in relation to an applied electric square pulse E. Below a (second) threshold value of the field strength and far from critical conditions, or under any conditions if the pulse is terminated at a time indicated by the dashed line, only birefringence is observed due to the formation of AJ, and Above the threshold of the field strength, close to critical conditions, and with a sufficiently long square pulse, turbidity contributes to the signal due to phase separation or/and percolation. The double wall of the particles symbolizes the water/oil interface. Symbols A, surfactant monomer An, microemulsion droplet (An), cluster LCmp, liquid-crystalline microphase or/and percolation structure. Primed symbols stand for polarized structures oriented parallel to E (- ) reversible step with respect to turning the field on or off (->) irreversible step. (Reprinted with permission from Refs. 6 and 41. Copyright 1989 and 1994 American Chemical Society.)...

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