Chemical Sequence Control of β-Sheet Assembly in Macromolecular Crystals of Periodic Polypeptides

• Published in: Science (American Association for the Advancement of Science) 1994-09, Vol.265 (5177), p.1427-1432
• Main Authors: Krejchi, Mark T., Edward D. T. Atkins, Waddon, Alan J., Fournier, Maurille J., Mason, Thomas L., Tirrell, David A.
• Format: Article
• Language: English
• Subjects: Amides; Amino Acid Sequence; Amino acids; Architecture; Base Sequence; Biological and medical sciences; Biotechnology; Computer Simulation; Crystal structure; Crystallization; Crystallography, X-Ray; Crystals; Fundamental and applied biological sciences. Psychology; Genetic engineering; Hydrogen Bonding; Infrared radiation; Magnetic Resonance Spectroscopy; Methods. Procedures. Technologies; Microscopy, Electron; Models, Molecular; Molecular biophysics; Molecular Sequence Data; Peptides - chemistry; Polymers; Polypeptides; Protein Engineering; Protein Structure, Secondary; Recombinant Proteins - chemistry; Recombinant Proteins - ultrastructure; Spectrum Analysis, Raman; Structure in molecular biology; Supramolecular structure; Wave diffraction; X ray diffraction
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.8073284

A family of uniform periodic polypeptides has been prepared by bacterial expression of the corresponding artificial genes, with the objective of exploring the potential for control of supramolecular organization in genetically engineered protein-based polymeric materials. The repeating units of the polypeptides consist of oligomeric alanylglycine sequences interspersed with glutamic acid residues inserted at intervals of 8 to 14 amino acids. Crystallization of such materials from formic acid produces β-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 formation 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.