Membrane crystallization has been recently proposed as an innovative technique for protein crystallization. In this system the membrane matrix acts as physical support separating two liquid subsystems which experience a double vapour/liquid equilibrium that induces solvent removal (in the vapour phase) in a controlled way, from one side of the membrane toward the other; the porous and hydrophobic nature of the polymeric surface even acts as promoter of heterogeneous crystallization. Membrane crystallizers can operate both in static and forced solution flow configurations (1,2). In the latter case, a condition of axial flow in laminar regime, induces the rectification of the Brownian motion of the incipient crystal embryos, that grow in a convective environment, thus allowing a better molecular interaction; this effect induces the formation of high structural quality and thus high diffracting power crystals, as demonstrated by X-ray analysis. Membrane crystallized proteins showed a considerable enhancement in crystallization kinetics: i.e. shorter induction times for crystals' appearance and higher growth rates if compared with traditional crystallization methodologies, starting from the same operative conditions (3); the hydrophobic and porous nature of the polymeric membrane surface is thought to be responsible of this effect. Membrane crystallization has been successfully applied for the crystallization of some proteins with different molecular weight, such as lysozyme, trypsins, lipase, ?-glucosidase, ?-carbonic anhydrase, catalase, both in static and dynamic configurations. By acting on the operative fluid dynamics parameters involved in the process, the crystallization kinetics has been controlled, thus allowing to tune the morphology (size and shape) of the crystalline materials produced. Higher levels of uniformity in size have been observed for these samples with respect to batch grown crystals (4). In this way, crystals with adequate characteristics in terms of shape, size, size distribution, in dependence on the specific application, have been grown. If thought that protein crystallization is already a difficult task, cause the high level of structural complexity of the bio-macromolecules, the development of an opportune technique that allows growing protein crystals and controlling the final properties of the them, would be an essential improvement in the overall field of life sciences and biotechnology. By this technique, in fact, it can be chosen to obtain high diffracting power crystals for structure determination by X-ray diffraction or to produce on large scale the starting crystalline material having the opportune morphology needed in cross-linked enzymes crystals applications. [1] Curcio, E., Di Profio, G., Drioli, E. (2003). J.Cryst. Growth. 247, 166-176. [2] Di Profio, G., Curcio, E., Drioli, E. (2005). J. Struct. Biol. 150, 41-49. [3] Di Profio, G., Curcio, E., Cassetta, A., Lamba, D., Drioli, E. (2003). J. Cryst. Growth. 257, 359-369. [4] Di Profio, G., Perrone, G., Curcio, E., Cassetta, A., Lamba, D., Drioli, E. (2005). Ind. Eng. Chem. Res. 44, 10005-10012.
Hydrophobic Microporous Membranes as Active Tools for Macromolecular Crystallization
Di Profio G;Drioli;
2006
Abstract
Membrane crystallization has been recently proposed as an innovative technique for protein crystallization. In this system the membrane matrix acts as physical support separating two liquid subsystems which experience a double vapour/liquid equilibrium that induces solvent removal (in the vapour phase) in a controlled way, from one side of the membrane toward the other; the porous and hydrophobic nature of the polymeric surface even acts as promoter of heterogeneous crystallization. Membrane crystallizers can operate both in static and forced solution flow configurations (1,2). In the latter case, a condition of axial flow in laminar regime, induces the rectification of the Brownian motion of the incipient crystal embryos, that grow in a convective environment, thus allowing a better molecular interaction; this effect induces the formation of high structural quality and thus high diffracting power crystals, as demonstrated by X-ray analysis. Membrane crystallized proteins showed a considerable enhancement in crystallization kinetics: i.e. shorter induction times for crystals' appearance and higher growth rates if compared with traditional crystallization methodologies, starting from the same operative conditions (3); the hydrophobic and porous nature of the polymeric membrane surface is thought to be responsible of this effect. Membrane crystallization has been successfully applied for the crystallization of some proteins with different molecular weight, such as lysozyme, trypsins, lipase, ?-glucosidase, ?-carbonic anhydrase, catalase, both in static and dynamic configurations. By acting on the operative fluid dynamics parameters involved in the process, the crystallization kinetics has been controlled, thus allowing to tune the morphology (size and shape) of the crystalline materials produced. Higher levels of uniformity in size have been observed for these samples with respect to batch grown crystals (4). In this way, crystals with adequate characteristics in terms of shape, size, size distribution, in dependence on the specific application, have been grown. If thought that protein crystallization is already a difficult task, cause the high level of structural complexity of the bio-macromolecules, the development of an opportune technique that allows growing protein crystals and controlling the final properties of the them, would be an essential improvement in the overall field of life sciences and biotechnology. By this technique, in fact, it can be chosen to obtain high diffracting power crystals for structure determination by X-ray diffraction or to produce on large scale the starting crystalline material having the opportune morphology needed in cross-linked enzymes crystals applications. [1] Curcio, E., Di Profio, G., Drioli, E. (2003). J.Cryst. Growth. 247, 166-176. [2] Di Profio, G., Curcio, E., Drioli, E. (2005). J. Struct. Biol. 150, 41-49. [3] Di Profio, G., Curcio, E., Cassetta, A., Lamba, D., Drioli, E. (2003). J. Cryst. Growth. 257, 359-369. [4] Di Profio, G., Perrone, G., Curcio, E., Cassetta, A., Lamba, D., Drioli, E. (2005). Ind. Eng. Chem. Res. 44, 10005-10012.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
