STRUCTURAL INVESTIGATION OF CYTOCHROME-F LANGMUIR-BLODGETT-FILMS WITHSCANNING-TUNNELING-MICROSCOPY - PROTEIN AGGREGATION

We have imaged Langmuir-Blodgett (LB) films of cytochrome f (Cyt f), t ransferred onto a gold film on mica substrate which has been covered w ith arachidic acid (three monolayers), with the scanning tunneling mic roscope. From these images, we have determined the structure of the Cy t f LB films (two monolayers) as a function of surface pressure (II) a nd ethanol concentration (ethanol:water) in the spreading solvent. We have observed aggregation of the Cyt f protein in films deposited at 1 5 and 20 mN/m with ethanol concentrations of 20%, 40%, and 80% in the spreading solvent. The LB films of Cyt f are mainly composed of aggreg ates a few hundred nm in size. Film morphology and aggregate sizes dep end upon the ethanol concentration and the surface pressure for transf er onto the solid substrate. (C) 1996 American Vacuum Society.