# Enabling synthesis and biological studies of homogeneous heparan sulfate and chondroitin sulfate glyco-polypeptides and proteoglycans

> **NIH NIH R01** · MICHIGAN STATE UNIVERSITY · 2024 · $290,733

## Abstract

Proteoglycans (PGs) are ubiquitous on mammalian cell surfaces and in the extracellular
matrix. PGs are made up of heparan sulfate or chondroitin sulfate glycosaminoglycan chains
covalently attached to the core protein through tetrasaccharide linkers. PGs play important roles
in many biological processes. However, due to the heterogeneity of naturally existing PGs, it is
extremely challenging to purify well-defined structures to study the structure and activity
relationship. Traditionally, the biological functions of PGs are believed to be dictated by the
glycosaminoglycan chains attached. Evidence is emerging that the core protein may significantly
impact the glycan activities. During the last grant period, homogeneous heparan sulfate and
chondroitin sulfate glycopeptides have been synthesized, providing access to these complex
molecules for the first time. However, the synthesis required total over 100 chemical steps to
complete a glycopeptide with a heparan sulfate chain, which limited the synthetic output.
Furthermore, with the current synthetic strategy, some of the common structural features in PGs
are not accessible. To overcome these challenges, in this renewal application, the power of the
biosynthetic enzymes will be harnessed to greatly expand the capability for PG synthesis. In aim
1, the key enzymes will be produced to generate the tetrasaccharide linkage region with the core
peptide, and to extend the glycan chain. Automated synthesis strategy will be developed to further
expedite the synthesis. In aim 2, ligation strategies will be established to synthesize glyco poly-
peptides with multiple glycan chains. This will provide a powerful tool to extend the poly-peptide
backbone, and to probe the hypothesis that the core protein can modulate glycan activities. In
aim 3, synthesis of a chondroitin sulfate proteoglycan bikunin like glycoprotein will be completed.
Bikunin is an approved drug to treat the potentially life-threatening sepsis conditions, and its
mechanism is currently unclear. Aided by the structurally well-defined synthetic bikunin, the
molecular mechanisms of the anti-inflammatory activities of bikunin will be established,
demonstrating the power of synthesis in expanding the understanding of the interesting biological
properties of these complex molecules.

## Key facts

- **NIH application ID:** 10752659
- **Project number:** 5R01GM072667-17
- **Recipient organization:** MICHIGAN STATE UNIVERSITY
- **Principal Investigator:** Xuefei Huang
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $290,733
- **Award type:** 5
- **Project period:** 2005-03-01 → 2025-12-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10752659

## Citation

> US National Institutes of Health, RePORTER application 10752659, Enabling synthesis and biological studies of homogeneous heparan sulfate and chondroitin sulfate glyco-polypeptides and proteoglycans (5R01GM072667-17). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10752659. Licensed CC0.

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