The Interaction of Globulin 7S from Amarantus Hypochondriacus with L-Dppc Langmuir Monolayer

The amaranth seed have a high contain of storage proteins (globulins and albumins) and have a better-balanced of essential amino acids than those found in cereals and legumes. The soy globulin extracts have become indispensable market commodities for increasing overall protein content and/or imparting functionality and texture, as well as enhanced nutritional value in a variety of food products. The aim of this work was to study the interactions of a model biomembrane made of L-a-dipalmitoyl phosphatidylcholine (L-DPPC) with globulin 7S seed storage protein from Amaranthus hypochondriacus. The Langmuir balance and Langmuir-Blodgett techniques were used to prepare monolayers of L-DPPC, globulin 7S, and mixtures of both. Ultra pure water (18.3 MW-cm) and phosphate-buffered water subphases were used for these experiments. Brewster Angle Microscopy (BAM) and Atomic Force Microscopy (AFM) were used to characterize the morphology of L-DPPC monolayer, protein monolayer and mixtures of protein with L-DPPC films at the air/water and air/buffer interfaces and subphases. The formation of protein-rich and L-DPPC-rich domains were found; however, both types of domains are liquid-like, since during compression are observed instabilities on the domain interface with BAM. Also, we observed that globulin aggregates tend to form filaments of molecular thickness and porous structures by means of AFM; this could be an indication of its tendency to form channels in vitro, which could be used by seeds in water transport for seed germination. The filaments can also form protein networks and can form agglutinated textures.