蛋白質結晶におけるマクロボンドと表面エネルギー(<小特集>バイオクリスタリゼーション)

抄録

The strengths of intermolecular contacts (macrobonds) in four lysozyme crystals were estimated based on the strengths of individual intermolecular interatomic interaction pairs. The periodic bond chain (PBC) of these macrobonds accounts for the morphology of protein crystals. The surface area of contact, polar coordinate representation of contact site, Coulombic contribution on the macrobond strength, and the surface energy of the crystal were also evaluated. Making use of the contact strengths and taking into account bond hydration, we estimated also crystal-water interfacial energies for different crystal faces. Comparing location of intermolecular contacts in different polymorphic crystal modifications we show that these contacts form a wide variety of patches on the molecular surface. The patches are located practically everywhere on the molecular surface except for the concave active site. It was also shown that the contacts, frequently involving water molecules, are formed with specific intermolecular hydrogen-bonds on the background of non-specific attractive electrostatic interactions. Macrobond strength is compared to those of associations in other protein complex systems.