Publications by authors named "W Jack Rink"

26 Publications

Decoration of Coiled-Coil Peptides with N-Cysteine Peptide Thioesters As Cyclic Peptide Precursors Using Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) Click Reaction.

Org Lett 2018 12 8;20(23):7493-7497. Epub 2018 Nov 8.

Institute of Organic and Biomolecular Chemistry, Georg-August Universität Göttingen , Tammannstraße 2 , 37077 Göttingen , Germany.

The development of a copper-catalyzed azide-alkyne cycloaddition (CuAAC) protocol for the decoration of coiled coils with N-cysteine peptide thioesters as cyclic peptide precursors is presented. The reaction conditions include tert-butanol/PBS as the solvent and CuSO/THPTA/ascorbate as the catalytic system. During these studies, partial formylation of N-terminal cysteine peptides is observed. Mechanistic analysis leads to identification of the formyl source and, hence, to the development of reaction conditions, under which the undesired side reaction was suppressed.
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http://dx.doi.org/10.1021/acs.orglett.8b03261DOI Listing
December 2018

De Novo Designed α-Helical Coiled-Coil Peptides as Scaffolds for Chemical Reactions.

Chemistry 2019 Feb 28;25(7):1665-1677. Epub 2018 Nov 28.

Institute of Organic and Biomolecular Chemistry, Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany.

Coiled coils (CCs) are well-understood protein-folding motifs. They appear in a variety of oligomer states and as homo- and heteromeric assemblies. This versatility and the general accessibility by de novo design makes them ideal building blocks for synthetic biology. This Minireview highlights the efforts being made in designing small peptide catalysts or reaction templates based on the CC scaffold. The first reports described autocatalysis or mediation of peptide ligation based on CC recognition. Over the years, the designs became more advanced, catalyzing ester hydrolysis, acyl transfer and redox reactions with partial enzyme-like reactivity. Due to the ability to control CC assembly, and, in heterodimeric systems, the association and dissociation, the CC motif has become a common peptide tag in chemical biology.
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http://dx.doi.org/10.1002/chem.201802849DOI Listing
February 2019

Evidence of an early projectile point technology in North America at the Gault Site, Texas, USA.

Sci Adv 2018 07 11;4(7):eaar5954. Epub 2018 Jul 11.

Texas Archaeological Research Laboratory, The University of Texas at Austin, 1 University Station, R7500, Austin, TX 78712, USA.

American archeology has long been polarized over the issue of a human presence in the Western Hemisphere earlier than Clovis. As evidence of early sites across North and South America continues to emerge, stone tool assemblages appear more geographically and temporally diverse than traditionally assumed. Within this new framework, the prevailing models of Clovis origins and the peopling of the Americas are being reevaluated. This paper presents age estimates from a series of alluvial sedimentary samples from the earliest cultural assemblage at the Gault Site, Central Texas. The optically stimulated luminescence age estimates (~16 to 20 thousand years ago) indicate an early human occupation in North America before at least ~16 thousand years ago. Significantly, this assemblage exhibits a previously unknown, early projectile point technology unrelated to Clovis. Within a wider context, this evidence suggests that Clovis technology spread across an already regionalized, indigenous population.
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http://dx.doi.org/10.1126/sciadv.aar5954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040843PMC
July 2018

Kinetic studies on strand displacement in designed parallel heterodimeric coiled coils.

Chem Sci 2018 May 17;9(18):4308-4316. Epub 2018 Apr 17.

Georg-August-Universität Göttingen , Institute of Organic and Biomolecular Chemistry , Tammannstraße 2 , 37077 Göttingen , Germany . Email:

Among the protein folding motifs, which are accessible by design, the parallel heterodimeric coiled coil is most frequently used in bioinspired applications and chemical biology in general. This is due to the straightforward sequence-to-structure relationships, which it has in common with all coiled-coil motifs, and the heterospecificity, which allows control of association. Whereas much focus was laid on designing orthogonal coiled coils, systematic studies on controlling association, for instance by strand displacement, are rare. As a contribution to the design of dynamic coiled-coil-based systems, we studied the strand-displacement mechanism in obligate heterodimeric coiled coils to investigate the suitability of the dissociation constants () as parameters for the prediction of the outcome of strand-displacement reactions. We use two sets of heterodimeric coiled coils, the previously reported N-A B and the newly characterized C-A B . Both comprise values in the μM to sub-nM regime. Strand displacement is explored by CD titration and a FRET-based kinetic assay and is proved to be an equilibrium reaction with half-lifes from a few seconds up to minutes. We could fit the displacement data by a competitive binding model, giving rate constants and overall affinities of the underlying association and dissociation reactions. The overall affinities correlate well with the ratios of values determined by CD-thermal denaturation experiments and, hence, support the dissociative mechanism of strand displacement in heterodimeric coiled coils. From the results of more than 100 different displacement reactions we are able to classify three categories of overall affinities, which allow for easy prediction of the equilibrium of strand displacement in two competing heterodimeric coiled coils.
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http://dx.doi.org/10.1039/c7sc05342hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5944379PMC
May 2018

Sequential Subterranean Transport of Excavated Sand and Foraged Seeds in Nests of the Harvester Ant, Pogonomyrmex badius.

PLoS One 2015 28;10(10):e0139922. Epub 2015 Oct 28.

Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America.

During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius) excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed the progress of nest deepening to 2 m and enlargement to 8 L in volume. Most of the excavation was completed within about 2 weeks, but the nest was doubled in volume after a winter lull. After 7 months, we excavated the nest and mapped its structure, revealing colored sand deposited in non-host colored layers, especially in the upper 30 to 40 cm of the nest. In all, about 2.5% of the excavated sediment was deposited below ground, a fact of importance to sediment dating by optically-stimulated luminescence (OSL). Upward transport of excavated sand is carried out in stages, probably by different groups of ants, through deposition, re-transport, incorporation into the nest walls and floors and remobilization from these. This results in considerable mixing of sand from different depths, as indicated in the multiple sand colors even within single sand pellets brought to the surface. Just as sand is transported upward by stages, incoming seeds are transported downward to seed chambers. Foragers collect seeds and deposit them only in the topmost nest chambers from which a separate group of workers rapidly transports them downward in increments detectable as a "wave" of seeds that eventually ends in the seed chambers, 20 to 80 cm below the surface. The upward and downward transport is an example of task-partitioning in a series-parallel organization of work carried out by a highly redundant work force in which each worker usually completes only part of a multi-step process.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139922PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624972PMC
June 2016