インスリンの凝集体が結晶成長に及ぼす効果

抄録

Several research works had been carried out by one (K.W.) of the authors, in order to understand a formation process of bovine insulin aggregates and crystals consisting of 2Zn-insulin hexamers. Concentration changes of the supersaturated solution of 2Zn-insulin during crystallization revealed that the aggregate of insulin at the early stage is composed of four insulin hexamers by a self-assembly theory. Light scattering from the solution during insulin aggregation, which was monitored by a dynamic light scattering (DLS) method, suggested that aggregates grow up to 600～800 nm in the solution phase by a diffusion limited aggregation (DLA) process of insulin hexamers. Images of insulin precipitates dried from the supersaturated solutions were taken by a canning electron microscopy (SEM). The images indicated that the insulin crystals are formed via spherical aggregates having about 1 mm size. Experiments of insulin crystallization under a strong magnetic field revealed that crystals grow up to about 2 mm in diameter in the bulk solution. Including our previous results, a formation process of insulin aggregates and crystals are discussed with comparison to a classical homogeneous nucleation mechanism. The effects of aggregates on quality of crystals are also discussed with reference to microgravity experiments.