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Poly(L-alanylglycine): Multigram-Scale Biosynthesis, Crystallization, and Structural Analysis of Chain-Folded Lamellae

Panitch, Alyssa and Matsuki, Kunio and Cantor, Eric J. and Cooper, Sharon J. and Atkins, Edward D. T. and Fournier, Maurille J. and Mason, Thomas L. and Tirrell, David A. (1997) Poly(L-alanylglycine): Multigram-Scale Biosynthesis, Crystallization, and Structural Analysis of Chain-Folded Lamellae. Macromolecules, 30 (1). pp. 42-49. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:PANm1997

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Abstract

The biosynthesis of poly(l-alanylglycine) (poly(AG)) was performed in high cell density cultures of recombinant Escherichia coli. The purity of the material was determined by amino acid analysis, elemental analysis, and ^1H NMR spectroscopy. Fed batch fermentation increased the yield of recombinant protein from levels of tens of milligrams per liter (typical of batch fermentation in rich media) to hundreds of milligrams per liter. Poly(AG) comprising 64 diads [(AG)_(64)] was recrystallized from dichloroacetic acid solutions in the form of texture-oriented chain-folded lamellae with a lamellar stack periodicity of 3.2 nm. The crystal structure within the lamellar core is similar in general, but different in detail, to the antiparallel β-sheet structure previously reported for oriented films of poly(AG) and fibers of Bombyx mori silk fibroin (silk II). The structure consists of polar antiparallel (ap) β-sheets, with repetitive folding through γ-turns every eighth amino acid (including the fold), stacking with like surfaces together. The wide-angle X-ray diffraction signals index on an orthorhombic unit cell with a (hydrogen bond direction) = 0.948 nm, b (sheet stacking direction) = 0.922 nm, and c (chain direction) = 0.695 nm. The stacking distance (b-value) is increased by about 3% in comparison with the previously reported structure of poly(AG), owing, we believe, to steric interaction at the lamellar fold surfaces. Random shears of approximately ±a/4 and shears of ±c/2 in the ac plane are required to obtain a good fit between the calculated and measured X-ray structure factors.


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http://dx.doi.org/10.1021/ma961059mDOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma961059mPublisherArticle
ORCID:
AuthorORCID
Tirrell, David A.0000-0003-3175-4596
Additional Information:Copyright © 1997 American Chemical Society. Received July 18, 1996; Revised Manuscript Received October 17, 1996. Publication Date (Web): January 13, 1997. Abstract published in Advance ACS Abstracts, December 15, 1996. This work was supported by grants from the Polymers and Genetics Programs of the National Science Foundation. NMR spectra were recorded in the University of Massachusetts NMR Facility, which is supported in part by the NSF Materials Research Science and Engineering Center at the University.
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Record Number:CaltechAUTHORS:PANm1997
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:PANm1997
Official Citation:Poly(L-alanylglycine):  Multigram-Scale Biosynthesis, Crystallization, and Structural Analysis of Chain-Folded Lamellae Alyssa Panitch, Kunio Matsuki, Eric J. Cantor, Sharon J. Cooper, Edward D. T. Atkins, Maurille J. Fournier, Thomas L. Mason, and David A. Tirrell Macromolecules 1997 30 (1), 42-49
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53444
Collection:CaltechAUTHORS
Deposited By: Anne Hormann
Deposited On:29 Jan 2015 23:31
Last Modified:03 Oct 2019 07:49

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