Introduction

Since its first reported application as a tool for protein or peptide ligation in 2004, Sortase A, a bacterial enzyme, has rapidly emerged as a research hotspot in fields such as biochemistry, proteomics, biomedicine, and bioengineering. Particularly in the development of antibody-drug conjugates (ADCs), Sortase A has played a pivotal role.

Fundamental Principles of Sortase A

Sortase A is a transpeptidase that primarily catalyzes transamidation reactions, enabling the precise attachment of various functional groups to proteins. It recognizes specific peptide sequences on target proteins, typically LPXTG (where X can be any amino acid), and cleaves between the threonine (T) and glycine (G) residues. This cleavage exposes a reactive threonine residue, which can form a new peptide bond with an oligoglycine-modified substrate, allowing the attachment of diverse molecules, including drugs, fluorophores, and other tags.

Advantages in ADC Drug Conjugation

Site-Specific Conjugation:

Sortase A-mediated antibody conjugation (SMAC) technology enables the efficient conjugation of toxins to antibodies at predefined sites, resulting in homogeneous drug-to-antibody ratio (DAR) products with high stability. This site-specific conjugation is crucial for consistent therapeutic efficacy and reduced off-target effects in ADCs.

Schematic diagram of antibody-drug conjugation mediated by SrtA

High Catalytic Efficiency:

Sortase A efficiently and specifically catalyzes covalent ligation reactions between proteins or peptides with specific sequences under mild reaction conditions, preserving the structure and function of the substrates.

Specific Recognition Sequence:

Sortase A can recognize substrates containing the LPXTG sequence and link them to various glycine-containing acceptors, making it applicable to a wide range of proteins and peptides.

Mild Reaction Conditions:

Sortase A functions under physiological conditions (e.g., neutral pH, room temperature), avoiding the degradation of proteins or peptides under extreme conditions.

Controllable Reaction Conditions:

By adjusting calcium ion concentration, substrate concentration, and reaction time, the catalytic reaction of Sortase A can be precisely controlled, enhancing reaction efficiency and yield.

Future Prospects

The application of Sortase A in the ADC field demonstrates its potential in biomedical technology. Through site-specific conjugation, Sortase A not only improves the stability and homogeneity of ADCs but also helps reduce off-target effects, offering more precise therapeutic strategies for cancer treatment. With further research and application, the prospects of Sortase A in protein engineering and drug development will continue to expand.

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