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PDBsum entry 3gxr
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References listed in PDB file
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Key reference
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Title
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Crystal structures of g-Type lysozyme from atlantic cod shed new light on substrate binding and the catalytic mechanism.
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Authors
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R.Helland,
R.L.Larsen,
S.Finstad,
P.Kyomuhendo,
A.N.Larsen.
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Ref.
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Cell Mol Life Sci, 2009,
66,
2585-2598.
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PubMed id
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Abstract
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Crystal structures of Atlantic cod lysozyme have been solved with and without
ligand bound in the active site to 1.7 and 1.9 A resolution, respectively. The
structures reveal the presence of NAG in the substrate binding sites at both
sides of the catalytic Glu73, hence allowing the first crystallographic
description of the goose-type (g-type) lysozyme E-G binding sites. In addition,
two aspartic acid residues suggested to participate in catalysis (Asp101 and
Asp90) were mutated to alanine. Muramidase activity data for two single mutants
and one double mutant demonstrates that both residues are involved in catalysis,
but Asp101 is the more critical of the two. The structures and activity data
suggest that a water molecule is the nucleophile completing the catalytic
reaction, and the roles of the aspartic acids are to ensure proper positioning
of the catalytic water.
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