The structure of His15 acetamide-modified hen egg-white lysozyme: a nice surprise from an old friend

2025/01/09 by José Malanho Silva, Jose Lanuza, F. Bruno +2 · 2 voices
Biochemistry, Genetics and Molecular Biology · Materials Science · #Enzyme Structure and Function #Protein Structure and Dynamics #Protein purification and stability

paper · pdf · doi:10.1107/s2053230x2500010x

openalex publication_date 2025/01/09 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04

Abstract

Hen egg-white lysozyme (HEWL) is a small polycationic protein which is highly soluble and stable. This has led to it becoming a `molecular laboratory' where chemical biological operations and structural techniques are tested. To date, HEWL accounts for 1233 PDB entries, roughly 0.5% of the total, making it the best-represented protein in the PDB. With the aim of unambiguously identifying the N atom of the His15 side chain that is most reactive towards iodoacetamide, the structure of chemically modified HEWL was determined by crystallizing it using the `15 minutes lysozyme' protocol. This protocol invariably yields tetragonal crystals of the unmodified protein. To our surprise, we found that the crystals of the modified protein had similar unit-cell parameters but that refinement was only possible when considering an orthorhombic system.

Citations

• UCSF Chimera—A visualization system for exploratory research and analysis

Discussions

• Can HEWL - the #StructuralBiology superstar with 1233 PDB entries - still hold surprises? We got the first structure with the H15-acetamide modification ➡️ Crystals grew in a rather unexpected orthorh [bsky, 4 points, 0 comments]
• Crystals of His15 acetamide-modified lysozyme had similar unit-cell parameters to the unmodified tetragonal form but refinement was only possible in an orthorhombic system #AcylatedLysozyme #Crystalli [bsky, 1 points, 0 comments]

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