Interaction of vitamin K1 and vitamin K2 with DMPC and their location in the membrane

Vitamin K1 and vitamin K2 play very important biological roles acting as members of chains of electron transport as antioxidants in membranes and as cofactors for the posttranslational modification of proteins that participate in a number of physiological functions such as coagulation. The interaction of these vitamins with dimyristoyl. phosphatidylcholine (DMPC) model membranes has been studied by using a biophysical approach. It was observed by using differential scanning calorimetry that both vitamins have a very limited miscibility with DMPC and they form domains rich in the vitamins at high concentrations. Experiments using X-ray diffraction also showed the formation of different phases as a consequence of the inclusion of either vitamin K at temperatures below the phase transition. However, in the fluid state a homogenous phase was detected and a decrease of the thickness of the membrane accompanied by an increase in the water layer thickness. 2H-NMR spectroscopy showed that both vitamins K induced ...