title: Ricin A-chain induces fusion of small unilamellar vesicles at neutral pH.
abstract: The interaction of ricin and its constituent polypeptides, the A- and B-chain, with small unilamellar vesicles of dipalmitoylphosphatidylcholine (DPPC) or dimyristoylphosphatidylcholine (DMPC) was investigated by means of differential scanning calorimetry measurements. The A-chain, at neutral pH, entirely shifted the endothermic peak of small unilamellar vesicles of DPPC from 37 degrees C to 41 degrees C at low protein/lipid ratios. The potency of either ricin or the B-chain to induce the shift of endothermic peak was much less than that of the A-chain. The A-chain was also found to cause mixing of endothermic peaks of DMPC vesicles and DPPC vesicles. These data strongly suggest that the A-chain has the ability to induce fusion of phospholipid vesicles.
authors.affiliation: Laboratory of Biochemistry, Faculty of Agriculture, Yamaguchi University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Utsumi
authors.forename: A
authors.initials: A
authors.lastname: Ide
authors.forename: G
authors.initials: G
authors.lastname: Funatsu
mesh_terms: D002152:Calorimetry, Differential Scanning; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers; D008561:Membrane Fusion / Q000187:drug effects*; D010713:Phosphatidylcholines; D012276:Ricin / Q000494:pharmacology*
chemical_list: D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D012276:Ricin