Water Behavior at the Phase Transition of Phospholipid Matrixes Assessed by FTIR Spectroscopy

Abstract

Lipid membranes are one of the most important biological matrixes in which biochemical processes take place. This particular lipid arrangement is driven by different water disposition interacting with it, which is related to different water states with different energy levels at the interphase. In our work, we report changes in water content and distinctive water states by Fourier transform infrared (FTIR) spectroscopy of this self-assembled matrix at different water contents and temperatures. To determine whether water properties at lipid interphases depend on the group of the lipid molecule at which it is bound the phase-transition temperature of 1,2-dimiristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-di-O-tetradecyl-sn-glycero-3-phosphocholine (14:0 diether PC) was followed by the changes in frequency of the different groups of the lipids by attenuated total reflection (ATR)-FTIR spectroscopy at different humidities. A comparison of these two lipids enables us to put into relevance the contribution of the CO groups as a hydration site. These changes were compared with those occurring at the water band, and a value of the enthalpic change was evaluated from them. The −OH stretching in the liquid water IR spectrum is the principal region used to understand its molecular organization (4000–3000 cm–1). The strength of hydrogen bonding depends on the cooperative/anticooperative nature of the surrounding hydrogen bonds, with the strongest hydrogen bonds giving the lowest vibrational frequencies. Thus, we can use water as a mirror of the membrane state in this kind of biological systems. Different phospholipids associate water at particular modes according to their structures. This may produce modulation of packing and hydration suitable for the incorporation of amino acids, peptides, and enzymes.

Antiproliferative, Antimicrobial and Antiviral Activity of β-Aryl-δ-iodo-γ-lactones, Their Effect on Cellular Oxidative Stress Markers and Biological Membranes

“…An increase in the wavenumber of the maximum of this band indicates that the location of the lipid phosphate polar head group is in less polar environments and that the head group hydration decreased. In turn, a decrease in the wavenumber of the maximum of this band indicates that the lipid phosphate polar head group is located in more polar environments and that head group hydration increased [62]. Similar changes are also observed when the membrane embeds compounds having OH groups in their structure, which may also form hydrogen bonds with the phosphoric group lipids, e.g., polyphenols, plant extracts, carotenoids, complexes of platinum [61,[63][64][65][66][67].…”

Breakdown of classical paradigms in relation to membrane structure and functions

“…This region is not only structurally important but also defines the thermodynamics of the bilayers. The layer of hydrated J o u r n a l P r e -p r o o f Journal Pre-proof groups and its coexistence with labile water makes that this region can be treated as a lattice solution [68]. A crucial concept in the definition of interphases, to introduce a new approach for understanding cell matrix as a complex system, is the excluded volume.…”

“…These degrees of freedom are a consequence of the balance between intermolecular interactions in the lattice and the thermal energy [68]. When the last predominates, fusion occurs.…”

“…It can be concluded that the connected populations appear at low water ratio and isolated ones at high. The amount of water in the chain region is concomitant with the hydration of the phosphate groups and modulated by the presence of carbonyl J o u r n a l P r e -p r o o f groups (CO) [68,125,126]. This means that in the so-called fluid region, the state of the CH 2 differs with the type of lipids.…”

“…In this regard, lipidomics show the complexity of plasma membranes in lipid composition and its implication in signaling processes. In this view lipidomics may derive in aquaomics for which it is understood that water acts as a mirror of lipids species and vice versa water properties determine lipid organization [68,187]. How do cells manage to tune these interphase properties to accomplished cell function is a matter of future and exciting discussion.…”