Author/Editor     Jerala, Roman; Almeida, Paulo F; Biltonen, Rodney L
Title     Simulation of the gel-fluid transition in a membrane composed of lipids with two connected acyl chains: application of a dimer-move step
Type     članek
Source     Biophys J
Vol. and No.     Letnik 71, št. 2
Publication year     1996
Volume     str. 609-15
ISSN     0006-3495
Language     eng
Abstract     Phospholipids have been treated as dimers on a hexagonal lattice, and a move has been introduced that allows the dimers to move and change their orientation on the lattice. Simulations have been performed in which phospholipid chains have been treated as being either independent or infinitely coupled thermodynamically with regard to their conformational state. Both types of simulation have reproduced well experimental heat-capacity curves of dipalmitoyl phosphatidylcholine small unilamellar vesicles. Apart from a different gel-fluid interaction parameter and a different number of unlike nearest-neighbor contacts, most of the averages and thermodynamic quantities were essentially the same in the two types of simulation. These results indicate that the transition is not first order and validate those of previous Monte Carlo simulations that have neglected the dimeric nature of phospholipids in the sense that they show that for the thermotropic transition the approximation of phospholipids as monomers is valid.
Descriptors     LIPOSOMES
MODELS, THEORETICAL
MOLECULAR CONFORMATION
1,2-DIPALMITOYLPHOSPHATIDYLCHOLINE
CALORIMETRY
DIMERIZATION
ENTROPY
GELS
THERMODYNAMICS