Thermal Behavior of Stearoylsphingomyelin-Cholesterol Dispersions

T. N. Estep, E. Freire, F. Anthony, Y. Barenholz, R. L. Biltonen, T. E. Thompson

Research output: Contribution to journalArticlepeer-review

Abstract

The thermotropic behavior of aqueous dispersions of stearoylsphingomyelin-cholesterol mixtures was examined by high-sensitivity differential scanning calorimetry. When less than 20 mol % cholesterol was mixed with the sphingomyelin and the samples were held at room temperature for 7-9 days before the initiation of calorimetric measurements, a sharp endotherm at 56-57 °C and a broad endotherm at 35-50 °C were observed. In addition, samples containing 15-20 mol % stearol exhibited a sharp endotherm at 43-45°C. If samples were held at room temperature for less than 2 h before the initiation of calorimetric analysis, the 56-57 °C endotherm was usually not seen. Instead, a combination of broad and sharp endotherms over the range of 35-50 °C was observed. Occasionally, exotherms were also observed within this temperature range. These results, along with those from previous studies, imply that a cholesterol-rich phase coexists with a cholesterol-poor phase in which the sphingomyelin molecules may exist in two distinctly different gel states.

Original languageEnglish (US)
Pages (from-to)7115-7118
Number of pages4
JournalBiochemistry
Volume20
Issue number25
DOIs
StatePublished - Dec 1981

ASJC Scopus subject areas

  • Biochemistry

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