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Publication Abstract from PubMed

A major challenge in protein folding is to identify and quantify specific structural determinants that allow native proteins to acquire their unique folded structures. Here we report the engineering of a 52-residue protein (Ala-14) that contains exclusively alanine residues at the hydrophobic a and d positions of a natural heptad-repeat sequence. Ala-14 is unfolded under normal solution conditions yet forms a parallel three-stranded alpha-helical coiled coil in crystals. Ala-14 trimers in the solid state associate with each other through the pairing of polar side chains and formation of an extended network of water-mediated hydrogen bonds. In contrast to the classical view that local intramolecular tertiary interactions dictate the three-dimensional structure of small single-domain proteins, Ala-14 shows that long range intermolecular interactions can be essential in determining the metastable alanine-zipper structure. A similar interplay between short range local and longer range global forces may underlie the conformational properties of the growing class of natively unstructured proteins in biological processes.

An alanine-zipper structure determined by long range intermolecular interactions.,Liu J, Lu M J Biol Chem. 2002 Dec 13;277(50):48708-13. Epub 2002 Oct 3. PMID:12368282^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.