Differential scanning calorimetric studies on the thermotropic phase behavior of dry and hydrated forms of N-acyltyramines

Abstract

In this paper, a homologous series of N-acyltyramine (NATA) – which is biosynthetic precursor for neuroactive lipids, N-acyldopamine – have been synthesized and their thermotropic phase transitions were characterized by differential scanning calorimetry (DSC). NATA undergoes a major sharp endothermic transition with the melting point of the hydrated samples occurs considerably at lower temperature compared to the dry samples. Thermodynamic parameters, transition enthalpy (ΔHt) and transition entropy (ΔSt), associated with the chain-melting phase transitions depends linearly on the number of carbon atoms. The contributions of each methylene unit to the transition enthalpy and entropy and the end contributions arising from the head group and the terminal group was determined and reported. These results are very important to understand the thermodynamics basis of NATA phase properties in other membrane lipids.