First Direct Observation of Impurity Effects on the Growth Rate of Tetragonal Lysozyme Crystals under Microgravity as Measured by Interferometry

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• 作者：Yoshihisa Suzuki ; Katsuo Tsukamoto ; Izumi Yoshizaki ; Hitoshi Miura ; Takahisa Fujiwara
• 刊名：Crystal Growth & Design
• 出版年：2015
• 出版时间：October 7, 2015
• 年：2015
• 卷：15
• 期：10
• 页码：4787-4794
• 全文大小：361K
• ISSN：1528-7505

文摘

The normal growth rates R and apparent step velocities (lateral growth rates of a spiral hillock) V of tetragonal hen egg-white lysozyme (HEWL) crystals were for the first time measured by Michelson interferometry in the international space station (as part of the NanoStep project) using commercialized HEWL samples containing 1.5% impurities. A significant increase in V under microgravity was confirmed compared to step velocities V_step on the ground, while a decrease in R was also confirmed compared to that in the purified solution under microgravity as expected. Because of exact measurement of growth rates, kinetic analyses of R were conducted as a function of supersaturation, 蟽 (蟽 鈮?ln(C/C_e), where C is the concentration; C_e is the solubility), using a spiral growth model and a two-dimensional (2D) nucleation growth model. For both models over a wide range of 蟽, R in the impure solution was significantly lower than that in the purified solution. The degree of the suppression of impurity effects was also evaluated using the difference in V_p and V_i, where V_p is the apparent step velocity in the purified solution, and V_i is that in the impure solution. The difference between V_p and V_i was smaller than the difference in step velocities on the ground, V_step,p and V_step,i, where V_step,p is the step velocity in the purified solution, and V_step,i is the step velocity in the impure solution.