天花粉蛋白晶体生长的斜锥形成核机制

Scalene cone-shaped nucleation in trichosanthin crystallization by atomic force microscopy

用原子力显微镜（AFM）研究了天花粉蛋白（Trichosanthin,TCS）晶体表面的斜锥形成核过程.对不同过饱和度下（σ=1.02~1.65）的TCS晶体成核过程进行了全方位的跟踪观察.发现在结晶前期,体系先采用线型生长,生长成链状聚集体,再进行侧向链间结合,最后形成不对称三维斜锥形核;在后期的成核过程中,TCS分子以尺寸不一的球形聚集体存在,并依次连接成串,进一步形成斜锥形核.通过AFM实验,详实地观测了TCS晶体生长的斜锥形成核过程,并从结构生物学角度阐释了这一成核现象的微观机制,给出了两种的成核途径.

An interesting nucleation mechanism of scalene cone-shaped nuclei of trichosanthin（TCS） is investigated by Atomic Force Microscopy（AFM）. The whole nucleation pathways are presented here at different supersaturations （σ=1.02-1.65）. In the early stages of TCS nucleation, molecules tend to form chainlike clusters and accumulate with more ones. Finally, many asymmetric 3-D scalene cone-shaped nuclei appear on the growing surfaces of TCS crystals. During the post-nucleational process TCS molecules form various size sphere-shaped clusters which are then connected together from big to small ones in sequence to form 3-D aggregates. Later they transform into scalene coneshaped ones before landing on the TCS crystal surfaces. These AFM results are used to elucidate nucleation pathways during the whole nucleation process and two models of nucleation are present.