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|3lhm, resolution 1.80Å ()|
CRYSTAL STRUCTURES OF THE APO-AND HOLOMUTANT HUMAN LYSOZYMES WITH AN INTRODUCED CA2+ BINDING SITE
The three-dimensional structures of apo- and holomutant human lysozymes (D86/92 lysozyme), in which a calcium binding site was designed and created for enhancing molecular stability by replacing both Gln86 and Ala92 with aspartic acids, were refined at 1.8-A resolution by x-ray crystallography. The overall structures and crystallographic thermal factors of all three proteins, the apo-, holo-D86/92, and the wild-type human lysozymes, were essentially identical; these results showed that the introduction of the calcium binding site did not affect either the overall structure or molecular rigidity of the proteins. However, structure analyses of the apo-D86/92 lysozyme revealed that the mutations affected the side chain conformation of residue 86 and hydrogen networks between the protein and the internal solvent molecules. In the structure of the holo-D86/92 lysozyme, seven oxygen ligands formed a slightly distorted pentagonal bipyramid around the calcium ion, indicating that the coordination around the calcium ion was quite similar to that in baboon alpha-lactalbumin. The pentagonal bipyramid coordination could be one of the most widely found and appropriate calcium binding schemes in proteins.
Crystal structures of the apo- and holomutant human lysozymes with an introduced Ca2+ binding site., Inaka K, Kuroki R, Kikuchi M, Matsushima M, J Biol Chem. 1991 Nov 5;266(31):20666-71. PMID:1939116
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
[LYSC_HUMAN] Defects in LYZ are a cause of amyloidosis type 8 (AMYL8) [MIM:105200]; also known as systemic non-neuropathic amyloidosis or Ostertag-type amyloidosis. AMYL8 is a hereditary generalized amyloidosis due to deposition of apolipoprotein A1, fibrinogen and lysozyme amyloids. Viscera are particularly affected. There is no involvement of the nervous system. Clinical features include renal amyloidosis resulting in nephrotic syndrome, arterial hypertension, hepatosplenomegaly, cholestasis, petechial skin rash.
[LYSC_HUMAN] Lysozymes have primarily a bacteriolytic function; those in tissues and body fluids are associated with the monocyte-macrophage system and enhance the activity of immunoagents.
About this Structure
- Inaka K, Kuroki R, Kikuchi M, Matsushima M. Crystal structures of the apo- and holomutant human lysozymes with an introduced Ca2+ binding site. J Biol Chem. 1991 Nov 5;266(31):20666-71. PMID:1939116