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Effects of amino acid side-chain volume on chain packing in genetically engineered periodic polypeptides

Cantor, Eric J. and Atkins, Edward D. T. and Cooper, Sharon J. and Fournier, Maurille J. and Mason, Thomas L. and Tirrell, David A. (1997) Effects of amino acid side-chain volume on chain packing in genetically engineered periodic polypeptides. Journal of Biochemistry, 122 (1). pp. 217-225. ISSN 0021-924X.

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The fidelity of bacterial protein synthesis allows the production of architecturally well-defined polymeric materials through precise control of chain length, sequence, stereochemistry, and interchain interactions. In the present paper, we examine the relation between amino acid residue volume and crystalline unit cell dimensions, in a set of periodic protein polymers of repeating unit sequence -(AlaGly)_3-X-Gly-, where X is Asn, Phe, Ser, Val, or Tyr. The proteins were overexpressed in Escherichia coli, purified by simple procedures based on acid/ethanol precipitation or insolubility in aqueous sodium dodecyl sulfate, and processed to form oriented crystalline mats by precipitation from formic acid under mechanical shear. X-ray diffraction analyses revealed that the basic structures of the -(AlaGly)_3-X-Gly- polymers are identical to that previously reported for [(AlaGly)_3-GluGly]_(36), [Krejchi, M.T., Atkins, E.D.T., Waddon, A.J., Fournier, M.J., Mason, T.L., and Tirrell, D.A. (1994) Science 265, 1427-1432], with the oligoalanylglycine segments forming antiparallel beta-sheets and the substituted amino acids occurring within three-residue folds at the lamellar surfaces. The X-ray diffraction signals for each member of the family index on an orthorhombic unit cell; the a-axis (hydrogen bond direction) and c-axis (chain direction) spacings remain invariant but the b-axis (sheet stacking direction) spacing increases with increasing volume of the substituted amino acid. The results obtained from a variant with alternating Glu and Lys substitution at the X position, together with the results previously reported for poly(L-alanylglycine) [Panitch, A., Matsuki, K., Cantor, E.J., Cooper, S.J., Atkins, E.D.T., Fournier, M.J., Mason, T.L., and Tirrell, D.A. (1997) Macromolecules 30, 42-49] are included for comparison. The average intersheet stacking distance (b/2) increases linearly with the volume of the amino acid inserted at position X. Because the chain-folded lamellar architecture adopted by these periodic polypeptides accommodates a wide range of residues differing in charge, steric bulk, and hydrophobicity, these results illustrate a new approach to the engineering of intermolecular interactions in polymeric solids.

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Tirrell, David A.0000-0003-3175-4596
Additional Information:© 1997 Japanese Biochemical Society. Received for publication, March 17, 1997. Supported by grants from the Polymers and Genetics Programs of the National Science Foundation (NSF), the NSF Materials Research Science and Engineering Center at the University of Massachusetts, the Engineering and Physical Sciences Research Council and the Biotechnology and Biological Sciences Council (Bristol University Molecular Recognition Center). We thank Joseph Cappello of Protein Polymer Technologies, Inc., for a gift of the p937.51 cloning vector. We also thank Kevin McGrath, Michael Dougherty, and Mary McTernan for early contributions to this work.
Funding AgencyGrant Number
Engineering and Physical Sciences Research Council (EPSRC)UNSPECIFIED
Biotechnology and Biological Sciences Research Council (BBSRC)UNSPECIFIED
Subject Keywords:artificial proteins, biomaterials, crystallization, fibrous proteins, X-ray diffraction
Issue or Number:1
Record Number:CaltechAUTHORS:20150108-171011842
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Official Citation:Eric J. Cantor, Edward D.T. Atkins, Sharon J. Cooper, Maurille J. Fournier, Thomas L. Mason, and David A. Tirrell Effects of Amino Acid Side-Chain Volume on Chain Packing in Genetically Engineered Periodic Polypeptides J Biochem (1997) 122 (1): 217-225
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53442
Deposited By: Anne Hormann
Deposited On:29 Jan 2015 23:55
Last Modified:03 Oct 2019 07:49

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