2-DIMENSIONAL CRYSTALLIZATION OF FERRITIN MOLECULES AT THE AIR-WATER-INTERFACE

Three kinds of dialkyl compounds, dimethyl-dioctadecyl-ammonium bromid e, sodium dioctadecyl-phosphate, and sodium dioctadecanoyl-sulphate, a re employed as monolayers adsorbing ferritin proteins at the air-water interface. After incubating the lipid monolayer on the water surface, proteins are injected into the subphase. After an elapsed time of bet ween 10 and 50 min, the lipid-ferritin complexes are horizontally tran sferred onto a carbon film and observed by transmission electron micro scope. Although the dialkyl-ammonium salt has a smaller adsorption rat e of proteins (3.2 x 10(9) molecules cm(-2) min(-1)) than those of pho sphate and sulphate (7.7 x 10(9) and 8.6 x 10(9) molecules cm(-2) min( -1), respectively), ammonium salt has the tendency to yield the best t wo-dimensional crystals of protein, and constructs small crystals cons isting of 10-100 proteins in a short incubation time, For the first ti me, it was confirmed from quantitative analysis that two-dimensional c rystal growth of proteins would require both the adsorbing ability and fluidity of the lipid monolayer.