Azides act as powerful synthetic tools capable of binding to biological macromolecules and selectively modifying enzymes, cells, viral particles, proteins and tissue lysates. Azido amino acids are valuable synthetic building blocks for peptide chemistry, biomacromolecules incorporation, etc.
Application of Azide Amino Acids
1. Application of Antibody-Drug Site-Specific Conjugation
Antibody-drug site-specific coupling can be achieved by introducing azido amino acids. Commonly used azido amino acids include azide-methyl-L-phenylalanine and azide-lysine. Antibodies introduced with azido amino acids can be fixed and quantitatively coupled to drug linkers to obtain antibody-drug couples with uniform drug-antibody ratios, high potency, stability and safety. An example is a Her2/neu antibody containing four different azido-lysine sites, each of which is capable of binding to either toxin auristatin For Pyrrolobenzodiazepines (PBD) dimer to produce an antibody-bound drug with a drug to antibody ratio greater than 1.9.
2. Application of Structural Studies of Proteins
The real-time observation of structural changes associated with protein function is of great research importance. The unnatural amino acid azidophenylalanine was introduced into the light-activated protein. As a probe, azidophenylalanine is able to reveal the changing characteristics and and dynamic nature of the light-driven structure of the protein. In addition, the azidophenylalanine conjugate has an azide asymmetric stretching vibrational extinction coefficient and high environmental response sensitivity. It is commonly used in the study of protein conformational properties due to its ability to detect protein hydration with high spatial resolution.
3. Application of Targeted Modification of Biomolecules
The introduction of amino acids with azide groups in proteins can provide specific reaction sites for the targeted modification of protein drugs. This has important implications for the design and development of novel biotechnology products.
Azidohomoalanine is a methionine analog that is well tolerated for protein binding in the body. By introducing azidohomoalanine in vivo, the original methionine in the viral structural protein was replaced. Azidohomoalanine-modified viral proteins are expressed and assembled into viral particles. The assembled virus particles can be detected at the single particle level, while the original normal methionine-containing virus particles cannot be detected. Thus, azide amino acids can modify viral proteins, which is useful for studying virion structure and virus-host interactions.
PEG modifiers mostly target lysine residues within proteins and do not selectively target specific sites for modification, which usually causes a reduction in protein activity and is detrimental to in vivo drug delivery. Targeted PEG modification of proteins can be achieved by the specific introduction of azido amino acids and their specific reaction with alkyne groups.