CALORIMETRIC INVESTIGATION OF PHOSPHATIDYLETHANOLAMINE IN MARINE-INVERTEBRATES

A method of differential scanning calorimetry was used to study the thermotropic behavior of crystalline phosphatidylethanolamine (PE)* samples from muscle tissue of nine species of marine invertebrates capute during summer. It was shown that the phase transition temperature (T(c)) and the largest share of the PE transition region lie in the temperature range below zero. A correlation was found between low PE phase transition temperatures and the presence in it of fatty acids with irregular arrangement of double bonds; non-methylene interrupted dienoic acids (NMID). A comparison of basic phase transition parameters for PE and phosphatidycholine (PC) was made. Symbasis of PE and PC thermotropic behavior was observed in the majority of the studied animals. The percentage value of the surplus enthalpy at temperatures above -1.7-degrees-C proved to be useful as an index of animals adaptation to low temperatures. It was demonstrated that in marine invertebrates, the main phospholipids of the membranes (PC and PE) with the universal fatty radical composition provide the necessary liquid-crystalline state of membranes within the whole temperature range of the habitat, thus accounting for the animals' broad adaptational capacity.