title: A lamellar complex of lecithin and poly-L-tyrosine.
abstract: Complexes of poly-L-tyrosine (PT) with dipalmitoyllecithin, synthetic, (DPL) and with egg lecithin (EL) have been obtained by precipitation from methanol-water solutions. Chemical analysis indicates that both lecithins bind PT up to a limiting ratio of about 4 tyrosine residues/lecithin molecule. DPL-PT complexes have a lamellar structure closely resembling lecithin itself. In fact, DPL and DPL-PT lamellae have very nearly the same thickness as precipitated from methanol-water, although their swelling behavior on resuspension in pure water is different. The complexes crystallize in the form of hexagonal platelets, some monolayers and some with terraced spiral growths, with a thickness of 50-55 A. In X-ray and electron diffraction they yield sharp reflections at 4.14 A which are characteristic of hexagonal packing of phospholipid paraffinic chains. The order-disorder transition temperature of this crystalline lattice, determined by differential scanning calorimetry, is somewhat higher in the complex than in pure DPL. Physical models consistent with these observations are discussed.
mesh_terms: D002151:Calorimetry; D003460:Crystallization; D046911:Macromolecular Substances; D000432:Methanol; D008854:Microscopy, Electron; D008956:Models, Chemical; D010169:Palmitic Acids; D010455:Peptides; D010713:Phosphatidylcholines; D011108:Polymers; D011485:Protein Binding; D013696:Temperature; D014443:Tyrosine; D014867:Water; D014961:X-Ray Diffraction
chemical_list: D046911:Macromolecular Substances; D010169:Palmitic Acids; D010455:Peptides; D010713:Phosphatidylcholines; D011108:Polymers; D014867:Water; D014443:Tyrosine; D000432:Methanol