Mt. Krejchi et al., CHEMICAL SEQUENCE CONTROL OF BETA-SHEET ASSEMBLY IN MACROMOLECULAR CRYSTALS OF PERIODIC POLYPEPTIDES, Science, 265(5177), 1994, pp. 1427-1432
A family of uniform periodic polypeptides has been prepared by bacteri
al expression of the corresponding artificial genes, with the objectiv
e of exploring the potential for control of supramolecular organizatio
n in genetically engineered protein-based polymeric materials. The rep
eating units of the polypeptides consist of oligomeric alanylglycine s
equences interspersed with glutamic acid residues inserted at interval
s of 8 to 14 amino acids. Crystallization of such materials from formi
c acid produces beta-sheet structures in the solid state, as shown by
vibrational spectroscopy, nuclear magnetic resonance spectroscopy, and
wide-angle x-ray diffraction. The diffraction results, together with
observations from electron microscopy, are consistent with the formati
on of needle-shaped lamellar crystals whose thickness is controlled by
the periodicity of the primary sequence. These results can be used to
control solid-state structure in macromolecular materials.