Thermotropic phase behavior of model membranes composed of phosphatidylcholines containing methyl iso-branched fatty acids. 1. Differential scanning calorimetric studies was written by Lewis, Ruthven N. A. H.;McElhaney, Ronald N.. And the article was included in Biochemistry in 1985.Reference of 3903-40-0 This article mentions the following:
The thermotropic phase behavior of aqueous dispersions of phosphatidylcholines (PCs) containing 1 of a series of Me iso-branched fatty acyl chains was studied by differential scanning calorimetry. These compounds exhibited a complex phase behavior on heating which included 2 endothermic events, a gel/gel transition, involving a mol. packing rearrangement between 2 gel-state forms, and a gel/liquid-crystalline phase transition, involving the melting of the hydrocarbon chains. The gel/liquid-crystalline transition was a relatively fast, highly cooperative process which exhibited a lower transition temperature and enthalpy than did the chain-melting transitions of saturated straight-chain PCs of similar acyl chain length. In addition, the gel/liquid-crystalline phase transition temperature was relatively insensitive to the composition of the aqueous phase. In contrast, the gel/gel transition is a slow process of lower cooperativity than the gel-liquid-crystalline phase transition and is sensitive to the composition of the bulk aqueous phase. The gel/gel transitions of the Me iso-branched PCs had very different thermodn. properties and depended in a different way on hydrocarbon chain length than did either the subtransitions or the pretransitions observed with linear saturated PCs. The gel/gel and gel/liquid-crystalline transitions were apparently concomitant for the shorter-chain iso-branched PCs, but diverged on the temperature scale with increasing chain length, with a pronounced odd/even alternation of the characteristic temperatures of the gel/gel transition. The observations were be rationalized by assuming that the stable conformation characteristic of these lipids at temperatures below the gel/gel transition temperature and their conformation in the liquid-crystalline state are such that direct interconversions between the 2 states is improbable and that such interconversions must proceed via an intermediate state or states. In the experiment, the researchers used many compounds, for example, 12-Methoxy-12-oxododecanoic acid (cas: 3903-40-0Reference of 3903-40-0).
12-Methoxy-12-oxododecanoic acid (cas: 3903-40-0) belongs to esters. Carboxylic acid esters of low molecular weight are colourless, volatile liquids with pleasant odours, slightly soluble in water. Esters contain a carbonyl center, which gives rise to 120° C–C–O and O–C–O angles. Unlike amides, esters are structurally flexible functional groups because rotation about the C–O–C bonds has a low barrier. Their flexibility and low polarity is manifested in their physical properties; they tend to be less rigid (lower melting point) and more volatile (lower boiling point) than the corresponding amides. Reference of 3903-40-0
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics