Self-assembly of soluble proteins on functionalized lipid layers: a tentative correlation between the fluidity properties of the lipid film and protein ordering

New series of amphiphilic structures are designed to exhibit various fluidi ty properties when spread at the air-water interface. The influence of the molecular structure of these lipids on the process of two-dimensional (2D) crystallization of the B subunit of DNA gyrase, a soluble protein, is inves tigated in terms of size of the crystals produced, protein ordering, and cr ystallization kinetics. Whereas no difference is observed concerning the me an size of the protein 2D crystals obtained on the different lipid supports , the ultimate protein ordering observable by electron microscopy using the negative-staining technique is more regularly attained with some of these new lipids. The most interesting point results from large discrepancies in crystallization kinetics as highly-ordered protein 2D crystals form within 6-24 h depending on the lipid layer structure. Thus, these new lipids revea l of special interest when studying proteins that suffer from extended incu bation time at 4 degrees C or higher temperature and lose their functionali ty. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.