Clearly Detectable, Kinetically Restricted Solid–Solid Phase Transition in cis -Ceramide Monolayers

FANANI, M. LAURA; BUSTO, JON V.; SOT, JESÚS; ABAD, JOSÉ L.; FABRÍAS, GEMMA; SAIZ, LEONOR; VILAR, JOSE M. G.; GOÑI, FÉLIX M.; MAGGIO, BRUNO; ALONSO, ALICIA

LANGMUIR

AMER CHEMICAL SOC

Lugar: Washington; Año: 2018 vol. 34 p. 11749 - 11749

0743-7463

phingosine [(2S, 3R, 4E)-2-amino-4-octadecene-1,3-diol] is the most common sphingoid base in mammals. Ceramides are N-acyl sphingosines. Numerous small variations on this canonical structure are known, including the 1-deoxy, the 4,5-dihydro, and many others. However, whenever there is a Δ4 double bond, it adopts the trans (or E) configuration. We synthesized a ceramide containing 4Z-sphingosine and palmitic acid (cis-pCer) and studied its behaviour in the form of monolayers extended on an air-water interface. Cis-pCer acted very differently from the trans isomer in that, upon lateral compression of the monolayer, a solid-solid transition was clearly observed at a mean molecular area ≤ 44 Å2.molecule-1, whose characteristics depended on the rate of compression. The solid-solid transition, as well as states of domain coexistence, could be imaged by atomic force microscopy and by Brewster-angle microscopy. Atomistic molecular dynamics simulations provided results compatible wi