The two faces of the purple membrane: Structural differences revealed by metal decoration

The two faces of the purple membrane are unambiguously distinguishable from each other in the electron microscope after metal decoration. Crystalline order is revealed on one of the two surfaces of the membrane. Membrane cracking and fragmentation upon drying is strongest on hydrophilic supports and becomes less severe with increasing hydrophobicity of the support. This behaviour is almost unaffected by the presence of low molecular weight, aqueous “sustains”, such as glucose or sucrose, and demonstrates the importance of surface interactions for the preservation of thin macromolecular assemblies in vacuo.