Metastable phase behavior of a sphingolipid analogue

Curatolo, William ; Bali, Anu ; Gupta, Chhitar M. (1982) Metastable phase behavior of a sphingolipid analogue Biochimica et Biophysica Acta (BBA) - Biomembranes, 690 (1). pp. 89-94. ISSN 0005-2736

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Official URL: http://dx.doi.org/10.1016/0005-2736(82)90242-5

Related URL: http://dx.doi.org/10.1016/0005-2736(82)90242-5

Abstract

The phase behavior of the sphingolipid analogue 1-palmitoyl-2-tridecanylcarbamyloxy-sn-glycero-3-phosphocholine (CM-PC) has been studied by differential scanning calorimetry. When CM-PC is cooled at rates > 5 K/min, subsequent heating runs exhibit metastable behavior: a low enthalpy exotherm is observed at about 9°C (ΔH = -(1-2)kcal/mol), followed by a high enthalpy endotherm at 38°C (ΔH = 13 kcal/mol). Systematic variation of cooling/heating protocols indicates that CM-PC exhibits two low temperature states, one metastable and the other stable. Cooling from the liquid crystalline state results in formation of the metastable low-temperature polymorph I, which must transform into the stable low-temperature polymorph II before the liquid crystalline state can be reached again. This metastable thermal behavior is virtually identical to that recently reported for synthetic palmitoyl cerebroside (Ruocco, M.J., Atkinson, D., Small, D.M., Skarjune, R.P., Oldfield, E. and Shipley, G.G. (1981) Biochemistry 20, 5957-5966) and for bovine brain n-acylcerebrosides (Curatolo, W. (1982) Biochemistry, 21, 1761-1764). The observation of the metastable phase behavior of CM-PC indicates that the sphingosine backbone is not a prerequisite for such metastable behavior. Furthermore, the carbamyl group in CM-PC is reversed in orientation compared with the amide of sphingolipids (-NH-CO- vs. -CO-NH-), suggesting that the intermolecular hydrogen bonding potential, rather than some highly specific steric or conformational constraint, is responsible for the observed metastability of sphingolipids.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
Keywords:Metastable State; Sphingolipid Analog; Differential Scanning Calorimetry; Phase Behaviour
ID Code:15983
Deposited On:16 Nov 2010 13:37
Last Modified:03 Jun 2011 04:56

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