Neutron Interferometry Studies of Vectorially-Oriented Single Monolayers of Membrane Proteins

Larry R. Kneller and Charles F. Majkrzak, NIST Center for Neutron Research, Gaithersburg, MD 20899 J.
Kent Blasie University of Pennsylvania Department of Chemistry, Philadelphia, PA 19104

Vectorially-oriented single monolayers of functional membrane proteins tethered to the surface of solid substrates may provide an ultrathin film whose macroscopic response is determined by the protein's molecular function. For example, cytochrome c or Ca2+-ATPase may be utilized to generate energy-dependent electron or ion transport across the film. Cytochrome c and detergent-solubilized Ca2+-ATPase can each be tethered to and thereby vectorially-oriented on soft surfaces of appropriate organic self-assembled monolayers chemisorbed on the surface of silicon substrates. Neutron reflectivity/interferometry data from cytochrome c monolayers and from Ca2+-ATPase monolayers have been collected on the NG1 reflectometer at NIST. Results of these experiments will provide the water distribution profiles within both monolayers and the detergent distribution profile within the Ca2+-ATPase monolayers.

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