Two-dimensional molecular packing of proteins

A technique involving the physical and/or chemical adsorption of molecules in the subphase to the interfacial Langmuir monolayer has been developed to arrange protein molecules such as ferritin, bacteriorhodopsin (BR) (purple membrane) and cytochrome b₅₆₂ in closely-packed two dimensional arrays. For better packing of molecules, site-directed mutagenesis of cytochrome b₅₆₂ was introduced to enhance the hydrophobicity or to stabilize the molecules by introducing a cystine linkage. The photoreaction cycle of BR was analysed. From the sequence analysis of newly isolated BR-like pigments, it was suggested that several amino acid residues around the retinal were conserved and formed a "retinal pocket".