Two-Dimensional Crystallization of Biological Macromolecules - Molecules: Nucleation, Aggregation and Crystallization - page 99

Fig. 1. 2D crystals of the sugar transporter melibiose permease from E. coli . The crys-
tals grow as tubes several micrometers in length.
buttons enclosed by a dialysis membrane, dialysis slides and bent capil-
laries. In order to control conditions special dialysis machines have been
constructed (Jap et al ., 1992).
A large number of parameters can be varied in order to find conditions
at which a particular purified membrane protein forms 2D crystals.
Among those listed in Table 1 a few can be pointed out as being of spe-
cial importance. Even if the detergent will be depleted or completely
removed, its properties can influence initial stages in formation of the pro-
teolipid complexes. The critical micellar concentration (CMC) of the
detergent will influence dialysis time when this method is used for deter-
gent removal. Low CMC detergents like Triton X-100 will require several
days of dialysis. The choice of phospholipids normally follows the prin-
ciple that it should mimic the natural environment of the protein. Chain
length and degree of saturation are important properties. The ratio between