An official website of the United States government
Heparin (H) and heparan sulfate (HS) belong to the glycosaminoglycan (GAG) family of oligosaccharides, and their sequences and sulfation patterns are known to regulate the functions of various proteins in biological processes. Among these, the 6- O -sulfation of HS/H contributes most significantly to the structural diversity and binding interactions. However, the synthesis of HS with defined sulfation patterns remains a major challenge. Herein, we report a highly efficient and programmable one-pot method for the synthesis of protected heparin pentasaccharides using thioglycoside building blocks with optimized relative reactivities to allow the selective deprotection and preparation of regiodefined sulfate derivatives.
more »
« less
This content will become publicly available on February 20, 2027
Chemical Strategies for Controlling Sulfation in Biomacromolecules
Sulfation is a fundamental post-translational modification that imparts negative charge and structural complexity to biomolecules, thereby regulating molecular recognition, signaling, and homeostasis across all domains of life. Yet, the ability to interrogate the biological functions of sulfation has long been hindered by the difficulty of constructing molecules with defined sulfation patterns. This Account summarizes our efforts to develop chemical strategies that enable precise control over sulfation in glycans and proteins. We describe an organobase-promoted sulfur(VI) fluoride exchange (SuFEx) chemistry that allows early stage, chemoselective O-sulfation across a broad substrate scope, providing a general solution to sulfate installation in complex settings. Building on this foundation, we introduce an iterative “clickable disaccharide” platform for the programmable assembly of sequence-defined heparan sulfate glycomimetics, enabling systematic dissection of sulfation-dependent glycan–protein interactions. Extending these concepts to the protein realm, we developed a fluorosulfate tyrosine strategy that installs latent sulfates into peptides and proteins, which can be unmasked under physiological conditions or light control via hydroxamic-acid-mediated Lossen rearrangement, offering spatiotemporal control of sulfation in living systems. Collectively, these approaches delineate a unified chemical framework for constructing and manipulating sulfated biomacromolecules with molecular precision, opening new opportunities to elucidate and engineer the biological roles of sulfation.
more »
« less
- Award ID(s):
- 2412505
- PAR ID:
- 10681966
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- ACS Chemical Biology
- Volume:
- 21
- Issue:
- 2
- ISSN:
- 1554-8929
- Page Range / eLocation ID:
- 189 to 209
- Subject(s) / Keyword(s):
- Anions Carbohydrates Chemical Synthesis Peptides And Proteins Post-Translational Modification
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Heparan sulfate (HS) glycosaminoglycans are widely expressed on the mammalian cell surfaces and extracellular matrices and play important roles in a variety of cell functions. Studies on the structure–activity relationships of HS have long been hampered by the challenges in obtaining chemically defined HS structures with unique sulfation patterns. Here, we report a new approach to HS glycomimetics based on iterative assembly of clickable disaccharide building blocks that mimic the disaccharide repeating units of native HS. Variably sulfated clickable disaccharides were facilely assembled into a library of mass spec-sequenceable HS-mimetic oligomers with defined sulfation patterns by solution-phase iterative syntheses. Microarray and surface plasmon resonance (SPR) binding assays corroborated molecular dynamics (MD) simulations and confirmed that these HS-mimetic oligomers bind protein fibroblast growth factor 2 (FGF2) in a sulfation-dependent manner consistent with that of the native HS. This work established a general approach to HS glycomimetics that can potentially serve as alternatives to native HS in both fundamental research and disease models.more » « less
-
Abstract Proteoglycans are core proteins associated with carbohydrate/sugar moieties that are highly variable in disaccharide composition, which dictates their function. These carbohydrates are named glycosaminoglycans, and they can be attached to proteoglycans or found free in tissues or on cell surfaces. Glycosaminoglycans such as hyaluronan, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparin/heparan sulfate have multiple functions including involvement in inflammation, immunity and connective tissue structure, and integrity. Heparan sulfate is a highly sulfated polysaccharide that is abundant in the periodontium including alveolar bone. Recent evidence supports the contention that heparan sulfate is an important player in modulating interactions between damage associated molecular patterns and inflammatory receptors expressed by various cell types. The structure of heparan sulfate is reported to dictate its function, thus, the utilization of a homogenous and structurally defined heparan sulfate polysaccharide for modulation of cell function offers therapeutic potential. Recently, a chemoenzymatic approach was developed to allow production of many structurally defined heparan sulfate carbohydrates. These oligosaccharides have been studied in various pathological inflammatory conditions to better understand their function and their potential application in promoting tissue homeostasis. We have observed that specific size and sulfation patterns can modulate inflammation and promote tissue maintenance including an anabolic effect in alveolar bone. Thus, new evidence provides a strong impetus to explore heparan sulfate as a potential novel therapeutic agent to treat periodontitis, support alveolar bone maintenance, and promote bone formation.more » « less
-
null (Ed.)Abstract Protein tyrosine O -sulfation (PTS) plays a crucial role in extracellular biomolecular interactions that dictate various cellular processes. It also involves in the development of many human diseases. Regardless of recent progress, our current understanding of PTS is still in its infancy. To promote and facilitate relevant studies, a generally applicable method is needed to enable efficient expression of sulfoproteins with defined sulfation sites in live mammalian cells. Here we report the engineering, in vitro biochemical characterization, structural study, and in vivo functional verification of a tyrosyl-tRNA synthetase mutant for the genetic encoding of sulfotyrosine in mammalian cells. We further apply this chemical biology tool to cell-based studies on the role of a sulfation site in the activation of chemokine receptor CXCR4 by its ligand. Our work will not only facilitate cellular studies of PTS, but also paves the way for economical production of sulfated proteins as therapeutic agents in mammalian systems.more » « less
-
The molecular interactions of sulfated glycans, such as heparin, with antithrombin (AT) and platelet factor 4 (PF4) are essential for certain biological events such as anticoagulation and heparin induced thrombocytopenia (HIT). In this study, a library including 84 sulfated glycans (polymers and oligomers) extracted from marine algae along with several animal-originated polysaccharides were subjected to a structure-activity relationship (SAR) study regarding their specific molecular interactions with AT and PF4 using surface plasmon resonance. In this SAR study, multiple characteristics were considered including different algal species, different methods of extraction, molecular weight, monosaccharide composition, sulfate content and pattern and branching vs. linear chains. These factors were found to influence the binding affinity of the studied glycans with AT. Many polysaccharides showed stronger binding than the low molecular weight heparin (e.g., enoxaparin). Fourteen polysaccharides with strong AT-binding affinities were selected to further investigate their binding affinity with PF4. Eleven of these polysaccharides showed strong binding to PF4. It was observed that the types of monosaccharides, molecular weight and branching are not very essential particularly when these polysaccharides are oversulfated. The sulfation levels and sulfation patterns are, on the other hand, the primary contribution to strong AT and PF4 interaction.more » « less
