Chemoenzymatic Synthesis of Nonasulfated Tetrahyaluronan with a Paramagnetic Tag for Studying Its Complex with Interleukin‐10

Abstract

Implants and artificial biomaterials containing sulfated hyaluronans have been shown to improve the healing of injured skin and bones. It is hypothesized that these effects are mediated by the binding of sulfated glycosaminoglycans (GAGs) to growth factors and cytokines, resulting in the sequestering of proteins to the wound healing site and in modulated protein activity. Given that no direct synthetic access to sulfated oligohyaluronans has been available, little is known about their protein binding and the structure of the resulting protein complexes. Here, the chemoenzymatic preparation of oligohyaluronans on the gram scale is described. Oligohyaluronans are converted into anomeric azides at the reducing end, enabling the attachment of analytical labels through an anomeric ligation reaction. A nonasulfated tetrahyaluronan-ethylenediaminetetraacetic acid derivative has been produced and used as a paramagnetic tag for the elucidation of the complex of this ligand with interleukin-10 using paramagnetic relaxation enhancement NMR analysis. The metal ion position is resolved with 1.0 Å, enabling a refined structural model of the complex.

Sulfated Hyaluronan Derivatives Modulate TGF-β1:Receptor Complex Formation: Possible Consequences for TGF-β1 Signaling

“…The obtained ESI-MS-spectra of the per-sulfated azide of HA dp4 showed multiple charged species and different numbers of attached TEA counter-ions as described in Köhling et al . 30 . The average sulfate content of 80% of all mass signals that were detected and assigned amounted to a value of 8.8 sulfate groups per ion.…”

“…After purification by dialysis, HA dp4 was obtained as nona-sulfate sodium salt (psHA, dp4) as described in Köhling et al . 30 .…”

One‐Pot Synthesis of Unprotected Anomeric Glycosyl Thiols in Water for Glycan Ligation Reactions with Highly Functionalized Sugars

“…Enzymatic conjugations are very useful, however, the available biocat-alysts and accessible structures are limited. [8] In contrast, thioglycosides are stable under both basic and acidic aqueous conditions.T hey are thus useful linker entities in bioconjugates and for the solid-phase synthesis of oligosaccharides. [6] Glycosyl azides have been used successfully in copper-assisted dipolar coupling reactions to furnish triazol-containing glycoconjugates, [7] although the glycosyl triazolyl linkage can be hydrolyzed by acids such as trifluoroacetic acid (TFA), as tandard reagent in the synthesis of (glyco)peptides.…”

“…[6] Glycosyl azides have been used successfully in copper-assisted dipolar coupling reactions to furnish triazol-containing glycoconjugates, [7] although the glycosyl triazolyl linkage can be hydrolyzed by acids such as trifluoroacetic acid (TFA), as tandard reagent in the synthesis of (glyco)peptides. [10] During our recent studies on the conjugation of glycosaminoglycans (GAG), [8] theo ligosaccharides of extracellular matrices,w e realized that glycosyl thiols are required in order to enable more flexible ligation reactions and to obtain stable glycoconjugates. [9] In addition, they can be applied as glycosyl donors through activation under oxidative or alkylating conditions.…”

Eintopfsynthese ungeschützter anomerer Glykosylthiole in Wasser für Glykan‐Ligationen mit hochfunktionalisierten Zuckern

“…[6] Glykosylazide wurden bereits erfolgreich in Kupfer-katalysierten dipolaren Cycloadditionen verwendet, wobei triazolhaltige Glykokonjugaten erzeugt wurden, [7] deren Glykosyl-Triazolyl-Verknüpfung allerdings durch Säuren wie Trifluoressigsäure (TFA), einem Standardreagenz in der Synthese von Glykopeptiden, hydrolysiert werden kann. [8] Dagegen sind Thioglykoside sowohl unter basischen als auch unter sauren Bedingungen stabil, sodass sie eine nützliche Verknüpfung in Biokonjugaten und in der Festphasensynthese von Oligosacchariden darstellen. [9] Darüber hinaus kçnnen sie unter oxidativen und alkylierenden Bedingungen aktiviert und als Glykosyl-Donoren verwendet werden.…”