Uptake of iron (III)-ethylenediamine-N, N, N′, N′-tetraacetic acid complex by phosphatidylcholine lipid film: Part I. Effect of bulk pH. (January 2018)

• Record Type: Journal Article
• Authors: Villeneuve, Masumi; Tanaka, Mihoko; Saito, Natsumi; Sakamoto, Hiroyasu; Hayami, Yoshiteru
• Is Part Of: Chemistry and physics of lipids. Volume 210(2018)
• Page Start: 1
• Page End: 13
• Publication Date: 2018-01
• Subjects: Phosphatidylcholine -- Metal complex -- Gibbs monolayer -- Planar film -- pH effect -- Molecular interaction; Lipids -- Periodicals; Lipids -- Periodicals; Lipides -- Périodiques; Lipids; Periodicals; Electronic journals; 547.77
• DOI: 10.1016/j.chemphyslip.2017.12.002
• Languages: English
• ISSNs: 0009-3084

Abstract

Graphical abstract: Highlights: A 3-solute capillary system with a polyprotic acid is analyzed thermodynamically. Uptake of Fe-edta by phosphatidylcholine lipid film is quantitatively evaluated. Substantial amount of Fe-edta is incorporated in the lipid films at low pH. Fe-edta is expelled from the lipid film at moderate to high pH. Abstract: We studied a ternary solutes aqueous solution of NaOH, iron (III)-ethylenediamine- N, N, N ′, N ′-tetraacetic acid complex (Fe-edta), and 1, 2-diheptanoyl- sn -glycero-3-phosphatidylcholine (DHPC)/air interface system to clarify the interactions between iron complexes and lipids with a phosphatidylcholine head group. The solution surface tension and pH were measured as functions of the total molality of NaOH, Fe-edta and DHPC, and the mole fractions of NaOH and DHPC. Rigorous thermodynamic equations were derived, in which the overall proton dissociation equilibria of Fe-edta and DHPC were taken into consideration, and applied to experimental data to obtain phase diagram of adsorption. It was found that (1) adsorption of Fe-edta at the solution/air interface with a DHPC monolayer was about 50–130 times higher than that without a DHPC monolayer and (2) when the bulk mole fraction of NaOH was high, Fe-edta tended to be expelled from the adsorbed film. The last finding suggests that the ambient pH significantly affects passive transport of the iron complex through a phospholipid-containing membrane into the cell interior.