Novel Bio-Conjugation Method Achieves High Efficiency and Stability for Protein Modification

A research team from the Department of Materials Science and Engineering at Pohang University of Science and Technology, led by Professor Seung Soo Oh and Dr. Hyesung Jo, has developed a new method for precisely modifying specific proteins within complex biological environments. Their findings were published in the Journal of the American Chemical Society.

Proteins are fundamental to human biology and play a critical role in the study of disease diagnosis and treatment. Techniques that modify proteins—such as attaching fluorescent tags to track cancer cells—are central to advancing diagnostics and drug development.

However, current protein bio-conjugation methods face significant limitations. Many are restricted to a narrow range of proteins, require genetic engineering, or risk disrupting protein function due to non-specific modifications. The core challenge has been achieving selective modification of specific proteins within living systems.

To address this, the team introduced a new strategy that combines deoxyoxanosine (dOxa) with aptamers—nucleic acid-based molecules that can recognize and bind to specific targets. This approach enables highly targeted modifications at precise sites on individual proteins.

Using this method, the researchers were able to attach dOxa to a single site out of 45 possible reactive locations on a target protein. The dOxa compound achieved nearly 100% conjugation efficiency within four hours in biological environments and remained stable for over a month at room temperature—making it roughly a million times more stable than conventional NHS ester-based reagents.

Notably, the team successfully applied this technique to bio-orthogonally label two key cancer biomarker proteins—PTK7 and nucleolin—in living cells. This allowed real-time observation of protein dynamics and shed new light on the roles these receptor proteins play in cancer cell development.

This marks the first time researchers have modified specific native proteins in biological systems without impairing their function.

Beyond cancer diagnostics and treatment, this technology holds promise for a wide range of applications. It could accelerate the development of next-generation antibody-drug conjugates (ADCs), enable advanced bioimaging tools that distinguish cancerous from healthy tissue, and support personalized therapies by precisely modulating protein activity.

Moreover, the ability to fine-tune enzyme function through site-specific protein modification could open new avenues in drug discovery and biological research.

“This technology will be widely utilized in fields such as protein-based therapeutics, bioimaging, and targeted drug delivery,”

Professor Seung Soo Oh.

“We’ve introduced an approach that allows for precise, targeted modification of proteins,” added Dr. Hyesung Jo, first author of the study. “Looking ahead, we aim to apply this method to investigate unknown cellular mechanisms and support the development of antibody-drug conjugates.”