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PDBsum entry 5zph
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Oxidoreductase
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PDB id
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5zph
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References listed in PDB file
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Key reference
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Title
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in crystallo thermodynamic analysis of conformational change of the topaquinone cofactor in bacterial copper amine oxidase.
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Authors
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T.Murakawa,
S.Baba,
Y.Kawano,
H.Hayashi,
T.Yano,
T.Kumasaka,
M.Yamamoto,
K.Tanizawa,
T.Okajima.
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Ref.
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Proc Natl Acad Sci U S A, 2019,
116,
135-140.
[DOI no: ]
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PubMed id
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Abstract
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In the catalytic reaction of copper amine oxidase, the protein-derived redox
cofactor topaquinone (TPQ) is reduced by an amine substrate to an
aminoresorcinol form (TPQamr), which is in equilibrium with a
semiquinone radical (TPQsq). The transition from TPQamr to
TPQsq is an endothermic process, accompanied by a significant
conformational change of the cofactor. We employed the humid air and
glue-coating (HAG) method to capture the equilibrium mixture of
TPQamr and TPQsq in noncryocooled crystals of the enzyme
from Arthrobacter globiformis and found that the equilibrium shifts more
toward TPQsq in crystals than in solution. Thermodynamic analyses of
the temperature-dependent equilibrium also revealed that the transition to
TPQsq is entropy-driven both in crystals and in solution, giving the
thermodynamic parameters that led to experimental determination of the crystal
packing effect. Furthermore, we demonstrate that the binding of product aldehyde
to the hydrophobic pocket in the active site produces various equilibrium states
among two forms of the product Schiff-base, TPQamr, and
TPQsq, in a pH-dependent manner. The temperature-controlled HAG
method provides a technique for thermodynamic analysis of conformational changes
occurring in protein crystals that are hardly scrutinized by conventional
cryogenic X-ray crystallography.
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