B. Baumeister et S. Matile, Rigid-rod beta-barrels as lipocalin models: Probing confined space by carotenoid encapsulation, CHEM-EUR J, 6(10), 2000, pp. 1739-1749
Herein, we describe the design, synthesis, structure, and function of synth
etic, supramolecular beta-barrel models. Assembly of octi(p-phenylene)s wit
h complementary -Lys-Leu-Lys-NH2 and Glu-Leu-Glu-NH2 side chains yielded wa
ter-soluble rigid-rod beta-barrels of precise length and with flexible diam
eter. A hydrophobic interior was evidenced by guest encapsulation. Host-gue
st complexes with planarized, monomeric beta-carotene within tetrameric rig
id-rod beta-barrels, and disc micellar astaxanthin J-aggregates surrounded
by about dodecameric rigid-rod "bicycle tires" were prepared from mixed mic
elles by dialytic detergent removal. The significance of these findings for
future bioorganic chemistry in confined, intratoroidal space is discussed
in comparison with pertinent biological examples.