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{{Theoretical_model}} | |||
==CONFORMATIONAL ENERGY STUDIES OF BETA-SHEETS OF MODEL SILK FIBROIN PEPTIDES. I. SHEETS OF POLY(ALA-GLY) CHAINS== | |||
<StructureSection load='1slk' size='340' side='right'caption='[[1slk]]' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SLK FirstGlance]. <br> | |||
</td></tr><tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1slk FirstGlance], [https://www.ebi.ac.uk/pdbsum/1slk PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1slk ProSAT]</span></td></tr> | |||
</table> | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
A new model structure is proposed for the silk I form of the crystalline domains of Bombyx mori silk fibroin and the corresponding crystal form of poly(L-Ala-Gly). It was deduced from conformational energy computations on stacked sheet structures of poly(L-Ala-Gly). The novel sheet structure contains interstrand hydrogen bonds but is composed of anti-parallel polypeptide chains whose conformation differs from that of the antiparallel beta-sheets that constitute the silk II structure. The strands of the new sheet have a two-residue repeat, in which the Ala residues adopt a right-handed and the Gly residues a left-handed sheet-like conformation. The computed unit cell is orthorhombic, with cell dimensions a = 8.94 A, b = 6.46 A, and c = 11.26 A. The model accounts for most spacings in the observed fiber x-ray diffraction patterns of silk I and of the silk-I-like form of poly(L-Ala-Gly), and it is consistent with nmr and ir spectroscopic data. As a test of the computations, the well-established beta-sheet structure of silk II and the corresponding form of poly(L-Ala-Gly) have been reproduced. The computed energies for the two forms of poly(L-Ala-Gly) indicate that the silk-II-like form is more stable, by about 1.0 kcal/mol per residue. The main difference between the two structures is the orientation of the Ala side chains of neighboring strands in each sheet. In the Pauling-Corey beta-sheet and in the silk II form, referred to as an "in-register" structure, the Ala side chains of every strand point to the same side of a sheet. In the silk I structure, referred to as "out-of-register," the side chains of Ala residues in adjacent strands point to opposite sides of the sheet. | |||
Conformational energy studies of beta-sheets of model silk fibroin peptides. I. Sheets of poly(Ala-Gly) chains.,Fossey SA, Nemethy G, Gibson KD, Scheraga HA Biopolymers. 1991 Nov;31(13):1529-41. PMID:1814502<ref>PMID:1814502</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 1slk" style="background-color:#fffaf0;"></div> | |||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Theoretical Model]] | |||
[[Category: Large Structures]] | |||
[[Category: Fossey, S A]] | |||
[[Category: Gibson, K D]] | |||
[[Category: Nemethy, G]] | |||
[[Category: Scheraga, H A]] | |||