Theoretical study of aliphatic chain structure in mono- and bilayers

Melting entropy and structure of aliphatic chains in mono and bilayers

“…Fig. 3 shows for palmitic chains (n = 16) the variation of conformational entropy S. The evolution of S in function of d is analogous to that previously obtained, with hexane chains [2]. This entropy vanishes when d is less than 4.8 A.…”

“…On the other hand, in liquid crystal, gauche conformations are possible; greater is the distance dI.,. between the chains [2], the more numerous are these conformations (see fig. 1).…”

“…We have recently calculated [ 1,2] some structural properties of aliphatic chains mono or bilayer. These calculations were based on the existence of rotation isomers and of interactions between chains (WIRI model).…”

“…There are the lengths of chain which usually exist in phospholipids of biological membranes. We have been able to calculate the mean structural properties of a hexane layer by determining at first the statistical weights of all the conformations of the two chains [2] . This calculation becomes impossible when the chains have more than 12 carbon atoms.…”

“…The passage from one state to another is effected by modifying the local conformations of a few bonds in the chain [7] . These deformations are effected at random, but taking into account the intra and intercatenary interactions, and steric hindrance (overlaping of the atoms with the wall of the hexagonal cell which encloses the two chains) [2]. (See fig.…”