X-Ray Study of Two-Dimensional Crystal-Liquid Phase Transition in the Purple Membrane

Abstract

X-ray diffraction study has been made on the crystal-liquid phase transition in the purple membrane fractionated from Halobacterium halobium cells. The transition takes place at 75°C when the membranes are dispersed in distilled water. Bragg peaks do not exhibit any discontinuous change during the phase transition. Critical scattering takes place associated with the phase transition. Edge of the hexagonal lattice increases by about 1 Å from 30° to 73°C.