A comparative calorimetric and spectroscopic study of the effects of cholesterol and of the plant sterols β-sitosterol and stigmasterol on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes.

We performed comparative DSC and FTIR spectroscopic measurements of the effects of β-sitosterol (Sito) and stigmasterol (Stig) on the thermotropic phase behavior and organization of DPPC bilayers. Sito and Stig are the major sterols in the biological membranes of higher plants, whereas cholesterol (Chol) is the major sterol in mammalian membranes. Sito differs in structure from Chol in having an ethyl group at C24 of the alkyl side-chain, and Stig in having both the C24 ethyl group and trans-double bond at C22.

A DSC and FTIR spectroscopic study of the effects of the epimeric coprostan-3-ols and coprostan-3-one on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes: Comparison with their 5-cholesten analogues.

We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five analogues on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (β-OH, α-OH or CO) and in the presence or absence of a double bond in ring B and in the orientation of rings A and B. The Δ(5) sterols/steroid have a trans rather than a cis ring A/B junction, and the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases in the order β-OH > α-OH > CO.

A DSC and FTIR spectroscopic study of the effects of the epimeric cholestan-3-ols and cholestan-3-one on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes: Comparison with their 5-cholesten analogs.

We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five analogs on the thermotropic phase behavior and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (β-OH, α-OH or C=O) and in the presence or absence of a double bond in ring B. In both the Δ(5) and saturated sterols/steroid series, the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases in the order β-OH > α-OH > C=O.

A DSC and FTIR spectroscopic study of the effects of the epimeric 4,6-cholestadien-3-ols and 4,6-cholestadien-3-one on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes.

We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five analogues on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (βOH, αOH or C=O) and in the position(s) of the double bond(s). In the Δ(5) sterols/steroid series, the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases markedly in the order βOH>αOH>C=O.

A DSC and FTIR spectroscopic study of the effects of the epimeric 4-cholesten-3-ols and 4-cholesten-3-one on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes: comparison with their 5-cholesten analogues.

We present the results of a comparative differential calorimetric and Fourier transform infrared spectroscopic study of the effect of cholesterol and five of its analogues on the thermotropic phase behaviour and organization of dipalmitoylphosphatidylcholine bilayer membranes. These sterols/steroids differ in both the nature and stereochemistry of the polar head group at C3 (βOH, αOH or C=O) and in the position of the double bond (C4-C5 in ring A or C5-C6 in ring B). In the three Δ(5) sterols/steroid series, the concentration of these compounds required to abolish the DPPC pretransition, inversely related to their relative ability to disorder gel state DPPC bilayers, decreases in the order βOH>αOH>C=O and these differences in concentration are significant.