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Updated: May 14, 2026
Synthesis and Structure Determination of µ-Conotoxin PIIIA Isomers with Different Disulfide Connectivities
Published on: October 2, 2018
Solution structures of two homologous venom peptides from Sicarius dolichocephalus
Nikolaus M Loening1, Zachary N Wilson, Pamela A Zobel-Thropp
1Chemistry Department, Lewis & Clark College, Portland, Oregon, United States of America. loening@lclark.edu
Abstract:
We present solution-state NMR structures for two putative venom peptides from Sicarius dolichocephalus. These peptides were identified from cDNA libraries created from venom gland mRNA and then recombinantly expressed. They are the first structures from any species of Sicarius spiders, and the first peptide structures for any haplogyne spiders. These peptides are homologous to one another, and while they have at most only 20% sequence identity with known venom peptides their structures follow the inhibitor cystine knot motif that has been found in a broad range of venom peptides.
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Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can be...