RESUMEN
The normal growth rates of the {110} faces of tetragonal hen egg-white lysozyme crystals, R, were measured as a function of the supersaturation σ parameter using a reflection type interferometer under µG at the International Space Station (NanoStep Project). Since water slightly evaporated from in situ observation cells during a long-term space station experiment for several months, equilibrium temperature T(e) changed, and the actual σ, however, significantly increased mainly due to the increase in salt concentration C(s). To correct σ, the actual C(s) and protein concentration C(p), which correctly represent the measured T(e) value in space, were first calculated. Second, a new solubility curve with the corrected C(s) was plotted. Finally, the revised σ was obtained from the new solubility curve. This correction method successfully revealed that the 2.8% water was evaporated from the solution, leading to 2.8% increase in the C(s) and C(p) of the solution.
Asunto(s)
Medio Ambiente Extraterrestre , Muramidasa/química , Nave Espacial , Temperatura , Agua/química , Cristalización , Solubilidad , VolatilizaciónRESUMEN
The growth rate vs. supersaturation of a lysozyme crystal was successfully measured in situ together with the crystal surface observation and the concentration measurements onboard the International Space Station. A Michelson-type interferometer and a Mach-Zehnder interferometer were, respectively, employed for real-time growth rate measurements and concentration field measurements. The hardware development, sample preparation, operation, and analysis methods are described.