PMID:15272156

Citation	Ruiz, F, Hazemann, I, Mitschler, A, Joachimiak, A, Schneider, T, Karplus, M and Podjarny, A (2004) The crystallographic structure of the aldose reductase-IDD552 complex shows direct proton donation from tyrosine 48. Acta Crystallogr. D Biol. Crystallogr. 60:1347-54
Abstract	The X-ray crystal structure of human aldose reductase (ALR2) in complex with the inhibitor IDD552 was determined using crystals obtained from two crystallization conditions with different pH values (pH 5 and 8). In both structures the charged carboxylic head of the inhibitor binds to the active site, making hydrogen-bond interactions with His110 and Tyr48 and electrostatic interactions with NADP+. There is an important difference between the two structures: the observation of a double conformation of the carboxylic acid moiety of the inhibitor at pH 8, with one water molecule interacting with the main configuration. This is the first time that a water molecule has been observed deep inside the ALR2 active site. Furthermore, in the configuration with the lower occupancy factor the difference electron-density map shows a clear peak (2.5sigma) for the H atom in the hydrogen bond between the inhibitor's carboxylic acid and the Tyr48 side-chain O atom. The position of this peak implies that this H atom is shared between both O atoms, indicating possible direct proton transfer from this residue to the inhibitor. This fact agrees with the model of the catalytic mechanism, in which the proton is donated by the Tyr48 hydroxyl to the substrate. These observations are useful both in drug design and in understanding the ALR2 mechanism.
Links	PubMed Online version:10.1107/S0907444904011370
Keywords	Aldehyde Reductase/antagonists & inhibitors; Aldehyde Reductase/chemistry; Aldehyde Reductase/metabolism; Binding Sites; Carboxylic Acids/chemistry; Crystallography, X-Ray; Enzyme Inhibitors/chemistry; Enzyme Inhibitors/metabolism; Enzyme Inhibitors/pharmacology; Fluorobenzenes/chemistry; Fluorobenzenes/metabolism; Fluorobenzenes/pharmacology; Humans; Hydrogen-Ion Concentration; Models, Molecular; Molecular Structure; NADP/chemistry; Protein Structure, Tertiary; Protons; Thiazoles/chemistry; Thiazoles/metabolism; Thiazoles/pharmacology; Tyrosine/chemistry; Tyrosine/metabolism
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:ALDR	enables	GO:0004032: alditol:NADP+ 1-oxidoreductase activity	ECO:0000269: experimental evidence used in manual assertion		F		Seeded From UniProt	complete

References

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