GROWTH KINETICS OF PROTEIN SINGLE CRYSTALS IN THE GEL ACUPUNCTURE TECHNIQUE. Abel Moreno¹, Juan Ma. Garcia-Ruiz² & Manuel Soriano-Garcia¹, ¹Instituto de Quimica-UNAM, C.U. Coyoacan 04510. Mexico, D.F., ²Instituto Andaluz de Ciencias de la Tierra. C.S.I.C.-Universidad de Granada Campus Fuentenueva s/n 18002 Granada, Spain

This work presents the growth kinetics of protein crystal growth in the gel acupuncture technique. This new method has been proposed previously for the growth of protein single crystals [1]. The main advantage of the technique is that the crystals are obtained inside an X-ray capillary tubes. The growth of single crystals of lysozyme (HEW), Thaumatin within capillary tubes was monitored by time-lapse video-microscopy. The crystals were obtained by diffusive transport of precipitating agent through capillaries of internal diameter ranging from 0.2 mm to 1.5 mm, using the gel acupuncture technique. For crystals growing from true protein solutions, the measured average growth rates varies with capillary diameter from 2.7 Å/s to 3.7 Å/s for thaumatin and from 2.8 Å/s to 22 Å/s for lysozyme. The measured average growth rates, for crystals growing into gelled protein solutions, were 1.8 Å/s for thaumatin and 2.5 Å/s for lysozyme. In all the cases, the trend in variation of the growth rate with time is similar and suggest that, for capillaries with internal diameter radius lower than 1.2 mm, protein crystals grow in gel and free solution under diffusive mass transport control. Finally, it is showed that the crystal growth rate depends on the height of the capillary tube where nucleation occurs and it is function of the internal diameter of the capillary tube.

Reference:1. Moreno, A. Ph. D. Thesis, Universidad de Granada, Spain. (1995).