Lysozyme C (Gallus gallus) (HEL) (HEL)

Hen Egg Lysozyme (HEL) is a 129-residue enzyme derived from Gallus gallus (chicken) that serves as a foundational model antigen in molecular immunology and drug discovery. Biologically, it is a glycoside hydrolase that catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in bacterial peptidoglycan, providing innate antibacterial defense by compromising cell wall integrity. In the pharmaceutical industry, HEL is not typically a therapeutic target for treating human disease; instead, it is used as a gold-standard 'toy' antigen for benchmarking antibody discovery platforms, such as phage and yeast display libraries, and for optimizing protein engineering tools like Rosetta. Its exceptionally well-defined crystal structure and diverse set of characterized epitopes (recognized by classic antibodies like D1.3 and HyHEL10) allow researchers to study antibody-antigen binding kinetics, affinity maturation, and paratope-epitope interactions with high precision. Furthermore, HEL is extensively utilized in transgenic mouse models (e.g., MD4 and ML5 strains) to investigate the fundamental mechanisms of B-cell tolerance, receptor signaling, and the development of B-cell malignancies like lymphoma.

Other names

Hen egg-white lysozymeChicken egg-white lysozymeMuramidaseGallus gallus lysozymeHEWL

Used as a model antigen to evaluate the binding affinity, specificity, and epitope binning of candidate monoclonal antibodies and CAR-T constructs in research and development settings.