The structure of formaldehyde-inhibited xanthine oxidase determined by 35 GHz 2H ENDOR spectroscopy

Muralidharan Shanmugam; Bo Zhang; Rebecca L. McNaughton; R. Adam Kinney; Russ Hille; Brian M. Hoffman

doi:10.1021/ja106432h

The structure of formaldehyde-inhibited xanthine oxidase determined by 35 GHz ²H ENDOR spectroscopy

Muralidharan Shanmugam, Bo Zhang, Rebecca L. McNaughton, R. Adam Kinney, Russ Hille^*, Brian M. Hoffman

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

21 Scopus citations

Abstract

The formaldehyde-inhibited Mo(V) state of xanthine oxidase (I) has been studied for four decades, yet it has not proven possible to distinguish unequivocally among the several structures proposed for this form. The uniquely large isotropic hyperfine coupling for ¹³C from CH₂O led to the intriguing suggestion of a direct Mo-C bond for the active site of I. This suggestion was supported by the recent crystal structures of glycol- and glycerol-inhibited forms of aldehyde oxidoreductase, a member of the xanthine oxidase family. ¹H and ²H ENDOR spectra of I(C ^1,2H₂O) in H₂O/D₂O buffer now have unambiguously revealed that the active-site structure of I contains a CH ₂O adduct of Mo(V) in the form of a four-membered ring with S and O linking the C to Mo and have ruled out a direct Mo-C bond. Density functional theory computations are consistent with this conclusion. We interpret the large ¹³C coupling as resulting from a "transannular hyperfine interaction".

Original language	English (US)
Pages (from-to)	14015-14017
Number of pages	3
Journal	Journal of the American Chemical Society
Volume	132
Issue number	40
DOIs	https://doi.org/10.1021/ja106432h
State	Published - Oct 13 2010

Funding

ASJC Scopus subject areas

General Chemistry
Biochemistry
Catalysis
Colloid and Surface Chemistry

Access to Document

10.1021/ja106432h

Cite this

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title = "The structure of formaldehyde-inhibited xanthine oxidase determined by 35 GHz 2H ENDOR spectroscopy",

abstract = "The formaldehyde-inhibited Mo(V) state of xanthine oxidase (I) has been studied for four decades, yet it has not proven possible to distinguish unequivocally among the several structures proposed for this form. The uniquely large isotropic hyperfine coupling for 13C from CH2O led to the intriguing suggestion of a direct Mo-C bond for the active site of I. This suggestion was supported by the recent crystal structures of glycol- and glycerol-inhibited forms of aldehyde oxidoreductase, a member of the xanthine oxidase family. 1H and 2H ENDOR spectra of I(C 1,2H2O) in H2O/D2O buffer now have unambiguously revealed that the active-site structure of I contains a CH 2O adduct of Mo(V) in the form of a four-membered ring with S and O linking the C to Mo and have ruled out a direct Mo-C bond. Density functional theory computations are consistent with this conclusion. We interpret the large 13C coupling as resulting from a {"}transannular hyperfine interaction{"}.",

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T1 - The structure of formaldehyde-inhibited xanthine oxidase determined by 35 GHz 2H ENDOR spectroscopy

AU - Shanmugam, Muralidharan

AU - Zhang, Bo

AU - McNaughton, Rebecca L.

AU - Kinney, R. Adam

AU - Hille, Russ

AU - Hoffman, Brian M.

PY - 2010/10/13

Y1 - 2010/10/13

N2 - The formaldehyde-inhibited Mo(V) state of xanthine oxidase (I) has been studied for four decades, yet it has not proven possible to distinguish unequivocally among the several structures proposed for this form. The uniquely large isotropic hyperfine coupling for 13C from CH2O led to the intriguing suggestion of a direct Mo-C bond for the active site of I. This suggestion was supported by the recent crystal structures of glycol- and glycerol-inhibited forms of aldehyde oxidoreductase, a member of the xanthine oxidase family. 1H and 2H ENDOR spectra of I(C 1,2H2O) in H2O/D2O buffer now have unambiguously revealed that the active-site structure of I contains a CH 2O adduct of Mo(V) in the form of a four-membered ring with S and O linking the C to Mo and have ruled out a direct Mo-C bond. Density functional theory computations are consistent with this conclusion. We interpret the large 13C coupling as resulting from a "transannular hyperfine interaction".

AB - The formaldehyde-inhibited Mo(V) state of xanthine oxidase (I) has been studied for four decades, yet it has not proven possible to distinguish unequivocally among the several structures proposed for this form. The uniquely large isotropic hyperfine coupling for 13C from CH2O led to the intriguing suggestion of a direct Mo-C bond for the active site of I. This suggestion was supported by the recent crystal structures of glycol- and glycerol-inhibited forms of aldehyde oxidoreductase, a member of the xanthine oxidase family. 1H and 2H ENDOR spectra of I(C 1,2H2O) in H2O/D2O buffer now have unambiguously revealed that the active-site structure of I contains a CH 2O adduct of Mo(V) in the form of a four-membered ring with S and O linking the C to Mo and have ruled out a direct Mo-C bond. Density functional theory computations are consistent with this conclusion. We interpret the large 13C coupling as resulting from a "transannular hyperfine interaction".

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