Hostname: page-component-cd9895bd7-7cvxr Total loading time: 0 Render date: 2024-12-21T16:05:34.945Z Has data issue: false hasContentIssue false
  • English
  • Français

The inorganic biochemistry of molybdoenzymes

Published online by Cambridge University Press:  17 March 2009

Robert C. Bray
Robert C. Bray
Affiliation:
The School of Chemistry and Molecular Sciences, Sussex University, Falmer, Brighton, Sussex, BN1 9QJ, UK
Get access Rights & Permissions [Opens in a new window]

Extract

Molybednum-containing enzymes (Coughlan, 1980; Spiro, 1985) occupy a significant place in the development of the field now termed inorganic biochemistry. The importance of the metal as a biological trace element depends on its involvement in the known, and perhaps other as yet unknown, molybdoenzymes. That it plays a role in biological nitrogen fixation, the process whereby the enzyme nitrogenase in the root nodules of plants converts atmospheric nitrogen into ammonia, was recognized in the 1930s. The metal is also a constituent of a variety of other enzymes, having first been found in a mammalian enzyme, xanthine oxidase, in the 1950s.

Type
Research Article
Information
Quarterly Reviews of Biophysics , Volume 21 , Issue 3 , August 1988 , pp. 299 - 329
Copyright
Copyright © Cambridge University Press 1988

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Adams, M. W. W. & Mortenson, L. E. (1985). Mo reductases: nitrate reductase and formate dehydrogenase. In Molybdenum Enzymes (Ed. Spiro, T. G.), pp. 519–593. New York: Wiley Interscience.Google Scholar
Anderson, R. F., Hille, R., Massey, V. (1986) The radical chemistry of milk xanthine oxidase as studied by radiation chemistry techniques. J. biol Chem. 261, 15870–15876.CrossRefGoogle ScholarPubMed
Avis, P. G., Bergel, F. & Bray, R. C. (1956), Cellular constituents. The chemistry of xanthine oxidase. III. Estimations of the co-factors and catalytic activities of enzyme fractions from cow's milk. J. chem. Soc. 1219–1226.CrossRefGoogle Scholar
Barber, M. J., Bray, R.C., Lowe, D. J. & Coughlan, M. P. (1976). Studies by electron-paramagnetic-resource spectroscopy and stopped-flow on the mechanism of action of turkey liver xanthine dehydrogenase. Biochem. J. 153, 297–307.CrossRefGoogle ScholarPubMed
Barber, M. J., Coughlan, M. P., Rajagopalan, K. V. & Seigel, L. M., (1982). Properties of the prosthetic groups of rabbit liver aldehyde oxidase: a comparison of molybdenum hydroxylase enzymes. Biochemistry 21, 3561–3568.CrossRefGoogle ScholarPubMed
Barber, M. J., May, H. D. & Ferry, J. G. (1986). Inactivation of formate dehydrogenase from Methanobacterium formicicum by cyanide. Biochemistry 25, 8150–8155.CrossRefGoogle Scholar
Berg, J. M. & Holm, R. H. (1985 a). A model for the active sites of oxo-transfer molybdoenzymes: synthesis, structure and properties. J. Am. chem. Soc. 107, 917–925.CrossRefGoogle Scholar
Berg, J. M. & Holm, R. H. (1985 b). A model for the active sites of oxo-transfer molybdoenzymes: reactivity, kinetics, and catalysis. J. Am. chem. Soc. 107, 925–932.CrossRefGoogle Scholar
Bordas, J., Bray, R. C., Garner, C. D., Gutteridge, S. & Hasnain, S. S. (1980). X-ray absorption spectroscopy of xanthine oxidase: the molybdenum, centres of the functional the desulpho forms. Biochem. J. 191, 499–508.CrossRefGoogle ScholarPubMed
Bray, R. C. (1961). Sudden freezing as a technique for the study of rapid reactions. Biochem. J. 81, 189–195.CrossRefGoogle Scholar
Bray, R. C. (1975). Molybdenum iron–sulphur flavin hydroxylases and related enzymes. In The Enzymes, 3rd edn vol. 12, pp. 299–419.Google Scholar
Bray, R. C. (1980). The reactions and the structures of molybdenum centres in enzymes. Advances in Enzymology and Related Areas of Molecular Biology 51, 107–165.Google ScholarPubMed
Bray, R. C. (1984). The structures and catalytic mechanisms of molybdenum centres in enzymes studied by e.p.r. and X-ray spectroscopy. In Flavins and Flavoproteins (ed. Bray, R. C.Mayhew, S. G. and Engel, P. C.), pp. 707–722. Berlin: de Gruyter.CrossRefGoogle Scholar
Bray, R. C. (1986). The nature of the high-pH-low-pH transition in sulphite oxidase and nitrate reductase. Polyhedron 5, 591–595.CrossRefGoogle Scholar
Bray, R. C. (1987). Recent studies on molybdenum centres in enzymes. Recueil Trav. chim. Pays-Bas 106, 301.Google Scholar
Bray, R. C. & George, G. N. (1985). Electron-paramagneteic-resonance studies using pre-steady-state kinetics and substitution with stable isotopes on the mechanism of action of molybdoenzymes. Biochem. Soc. Trans. 13, 560–567.CrossRefGoogle ScholarPubMed
Bray, R. C. & Gutteridge, S. (1982). Numbers and exchangeability with water of oxygen-17 atoms coupled to molybdenum(v) in different reduced forms of xanthine oxidase. Biochemistry 212, 5992–5999.CrossRefGoogle Scholar
Bray, R. C. & Knowles, P. F. (1968). Electron spin resonance in enzyme chemistry: the mechanism of action of xanthine oxidase.Proc. R. Soc. hand. A302, 351–353.Google Scholar
Bray, R. C. & Meriwether, L. S. (1966). Electron spin resonance of xanthine oxidase substituted with molybdenum-95. Nature, Lond. 212, 467–469.CrossRefGoogle ScholarPubMed
Bray, R. C. & Vänngård, T. (1969). ‘Rapidly appearing’ molybdenum electron paramagnetic resonance signals from reduced xanthine oxidase. Biochem. J. 114, 725–734.CrossRefGoogle ScholarPubMed
Bray, R. C., Barber, M. J., Lowe, D. J., Fox, R. & Cammack, R. (1975). Mechanisms of electron transfer within multicomponent oxidative enzymes illustrated by studies on xanthine oxidase. FEBS Proceedings 40, 159–172.Google Scholar
Bray, R. C., Barber, M. J. & Lowe, D. J. (1978). Electron-paramagnetic-resonance spectroscopy of complexes of xanthine oxidase with xanthine and uric acid. Biochem J. 171, 653–658.CrossRefGoogle ScholarPubMed
Bray, R. C., George, G. N., Gutteridge, S., Norlander, L., Stell, J. P. & Stubley, C. (1982 a). Studies by electron–paramagnetic resonance spectroscopy of the molybdenum centre of aldehyde oxidase. Biochem. J. 203, 263–267.CrossRefGoogle ScholarPubMed
Bray, R. C., Lamy, M. T., Gutteridge, S., & Wilkinson, T. (1982 b). Evidence from electron-paramagnetic-resonance spectroscopy for a complex of sulphite ions with the molybdenum centre of sulphite oxidase. Biochem. J. 201, 241–243.CrossRefGoogle ScholarPubMed
Bray, R. C., George, G. N., Lange, R. & Meyer, O. (1983 a). Studies by e.p.r. spectroscopy of carbon monoxide oxidases from Pseudomonas carboxydovorans and Pseudomonas carboxydohyrogena. Biochem. J. 211, 687–694.CrossRefGoogle Scholar
Bray, R. C., Gutteridge, S., Lamy, M. T. & Wilkinson, T. (1983 b). Equilibria amongst different molybdenum (v)-containing species from sulphite oxidase: evidence from a halide ligand of molybdenum in the low-pH species. Biochem. J. 211, 227–236.CrossRefGoogle ScholarPubMed
Bray, R. C., George, G. N., Hawkes, T. R. & Morpeth, F. F. (1983 c). Information on the structures and action of molybdenum centres in enzymes from e.p.r. studies with inhibitors. In Some Recent Developments in the Chemistry of Chromium, Molybdenum and Tungsten, (ed. Dilworth, J. R. and Lappert, M. F.), P.L7. Royal Soc. Chem. Dalton, London.Google Scholar
Bray, R. C., George, G. N., Gutteridge, S., Morpeth, F. F. & Turner, N. (1984), ‘Type 1’ and ‘type 2’ Rapid and Slow e.p.r. signals from the molybdenum centres of molybdenum-containing hydroxylylases and their significance. In Flavins and Flavoproteins (ed. Bray, R. C.Engel, P. C. and Mayhew, S. G.), pp. 691–694. Berlin: de Gruyter.CrossRefGoogle Scholar
Bray, R. C., George, G. N., Gutteridge, S., Bergmann, F. & Barman, T. (1987) (unpublished work).Google Scholar
Cleland, W. E., Barnhart, K. M., Yamanouchi, K., Collison, D., Mabbs, F. E., Ortega, R. B. & Enemark, J. H. (1987). Syntheses, structures and spectroscopic properties of six-coordinate mononuclear oxo–Mo(v) complexes stabilized by the hydroxotris(3, 5-dimethyl-1-pyrazolyl)borate ligand. Inorg. Chem. 26, 1017–1025.CrossRefGoogle Scholar
Cock, M.Lightfoot, D. A., Walters, D. E. & Wootton, J. C. (1987) (unpublished work).Google Scholar
Coughlan, M. P. (1980). Molybdenum-containing Enzymes. Oxford: Pergamon.Google Scholar
Coughlan, M. P., Mehra, R. K., Barber, M. J. & Siegel, L. M. (1984). Optical and electron paramagnetic resonance spectroscopic studies on purine hydroxylase II from Aspergillus nidulans. Arch. Biochem. Biophys. 229, 596–603.CrossRefGoogle ScholarPubMed
Cramer, S. (1983). Molybdenum enzymes: a survey of structural information from EXAFS and EPR spectroscopy. In Advances in Inorganic and Bioinorganic mechanisms, vol. 2 (ed. Sykes, A. G.), pp. 259–316. New York: Academic Press.Google Scholar
Cramer, S. P. & Hille, R. (1985). Arsenite-inhibited xanthine oxidase – determination of the Mo–S–As geometry by EXAFS. J. Am. chem. Soc. 107, 8164–8169.CrossRefGoogle Scholar
Cramer, S. P. & Stiefel, E. I. (1985). Chemistry and biology of the molybdenum cofactor. In Molybdenum Enzymes, ed. Spiro, T. G. pp. 411–441, New York: Wiley Interscience.Google Scholar
Cramer, S.P., Wahl, R. & Rajagopalan, K. V. (1981). Molybdenum sites of sulfite oxidase and xanthine dehydrogenase. A comparison by EXAFS. J. Am. chem. Soc. 103, 7721–7727.CrossRefGoogle Scholar
Cramer, S. P., Moura, J. J. G., Xavier, A. V. & Le Gall, J. (1984 a). Molybdenum EXAFS of the Desulfovibrio gigas Mo(2Fe–2S) protein – structural similarity to ‘Desulfo’ xanthine dehydrogenase. J. inorg. Biochem. 20, 275–280.CrossRefGoogle ScholarPubMed
Cramer, S. P., Solomonson, L. P., Adams, M. W. W. & Mortenson, L. E. (1984 b). Molybdenum sites of Escherichia coli and Chlorella vulgaris nitrate reductase: a comparison by EXAFS. J. Am. chem. Soc. 106, 1467–1471.CrossRefGoogle Scholar
Cramer, S. P., Liu, C. L., Mortenson, L. E., Spence, J. T., Liu, S. M., Yamamoto, I. & Ljungdahl, L. G. (1985). Formate dehydrogenase molybdenum and tungsten sites – observation by EXAFS of structural differences, J. inorg. Biochem. 23, 119–124.CrossRefGoogle ScholarPubMed
Dalton, H., Lowe, D. J., Pawlik, R. T. & Bray, R. C. (1976). Studies by electronparamagnetic-resonance spectroscopy on the mechanism of action of xanthine dehydrogenase from Veillonella alcalescens. Biochem. J. 153, 287–295.CrossRefGoogle Scholar
Del Campillo-Campbell, A.Campbell, A. (1982). Molybdenum cofactor requirement for biotin sulfoxide reduction in Escherichia coli. J. Bad. 149, 469–478.Google ScholarPubMed
Dowerah, D., Spence, J. T., Singh, R.Wedd, A. G., Wilson, G. C., Farchione, F., Enemark, J., Kristofzski, J. & Bruck, M. (1987) Molybdenum(vi) and molybdenum(v) complexes with N, N′-dimethyl-N, N′-bis-(2-mercaptophenyl) ethylenediamine. Electrochemical and electron paramagnetic resonance models for the molybdenum(vi/v) centers of the molybdenum hydroxylases and related enzymes. J. Am. chem. Soc. 109, 5655–5665.CrossRefGoogle Scholar
Ehrenberg, A. & Bray, R. C. (1987) (unpublished work).Google Scholar
Farchione, F., Hanson, G. R., Rodrigues, C. R.Bailey, T. D., Bagchi, R. N., Bond, A. M., Pilbrow, J. R. & Wedd, A. G. (1986). Generation of a cis-[MovO(OH)] center: 1H- and 17O-superhyperfine parameters relevant to molybdoenzymes. J. Am. Chem. Soc. 108, 831–832.CrossRefGoogle Scholar
von Felten, H., Wernli, B., Gamsjäger, H. & Baertschi, P. (1978). Oxygen exchange between oxo-anions and water in basic media: molybdate(2-) and tungstate(2-). J. Chem. Soc. Dalton 496–500.CrossRefGoogle Scholar
Galtigny, & Scazzocchio, C. (1987). Unpublished work.Google Scholar
Garner, C. D., Hyde, M. R., Mabbs, F. E., & Routledge, V. I. (1975). Kinetics and mechanism of oxidation of trichloro-oxobis-(triphenylphophine oxide)molybdenum(v) by nitrate in dichloromethane. J. chem. Soc. Dalton 1180–1186.CrossRefGoogle Scholar
George, G. N. (1983). E.p.r. studies on the molybdenum site of xanthine oxidase. D.Phil. Thesis, University of Sussex, U.K.Google Scholar
George, G. N. (1984). Coupling between Mo(v) and reduced Fe/Si centres in aldehyde oxidase and xanthine oxidase. In Flavins and Flavoproteins (ed. Bray, R. C.Engel, P. C. and Mayhew, S. G.), pp. 325–330. Berlin: de Gruyter.CrossRefGoogle Scholar
George, G. N. (1985). The proton spin–flip lines of Mo(v) e.p.r. signals from sulfite oxidase and xanthine oxidase. J. magn. Reson. 64, 384–394.Google Scholar
George, G. N. & Bray, R. C. (1983 a). Formation of the inhibitory complex of pmercuribenzoate with xanthine oxidase, evaluation of hyperfine and quadrupole couplings of mercury to molybdenum (v) from the electron paramagnetic resonance spectrum, and structure of the complex. Biochemistry 22, 5443–5452.CrossRefGoogle Scholar
George, G. N. & Bray, R. C. (1983 b). The reaction of arsenite ions with the molybdenum centre of milk xanthine oxidase. Biochemistry 22, 1013–1021.CrossRefGoogle ScholarPubMed
George, G. N. & Bray, R. C. (1988). Studies by electron paramagnetic resonance spectroscopy of xanthine oxidase enriched with 95Mo and with 97Mo. Biochemistry (in press).CrossRefGoogle Scholar
George, G. N., Bray, R. C., Morpeth, F. F. & Boxer, D. H. (1985). Complexes with halides and other anions of the molybdenum centre of nitrate reductase from Escherichia coli. Biochem. J. 227, 925–931.CrossRefGoogle ScholarPubMed
George, G. N., Bray, R. C. & Cramer, S. P. (1986 a). Extended X-ray absorption fine structure studies of transient species during xanthine oxidase turnover by using rapid freezing. Biochem. Soc. Trans. 14, 651–652.CrossRefGoogle Scholar
George, G. N., Hawkes, T. R., Jones, G. D. & Bray, R. C. (1986 b). Studies by electron paramagnetic resonance spectroscopy of the environment of the metal in the molybdenum cofactor of molybdenum-containing enzymes. Polyhedron 5, 587–589.CrossRefGoogle Scholar
George, G. N., Cramer, S. P., Turner, N. A., Boxer, D. H. & Bray, R. C. (1987) (unpublished work)Google Scholar
Goodman, B. A. & Raynor, J. B. (1970). Electron spin resonance of transition metal complexes. Adv. inorg. Chem. Radiochem. 13, 135–362.CrossRefGoogle Scholar
Groeneveld, C. M., Feiters, M. C., Hassnain, S. S., van Rijn, J., Reedijh, J. & Canters, G. W. (1986). The pH and redox-state dependence of the copper site in azurin from Pseudomonas aeruginosa as studied by EXAFS. Biochem. biophys. Ada 873, 214–227.Google Scholar
Gutteridge, S., (1987) (unpublished work).Google Scholar
Gutteridge, S. & Bray, R. C. (1980). Oxygen-17 splitting of the Very Rapid molybdenum(v)e.p.r. signal from xanthine oxidase: rate of exchange with water of the coupled oxygen atom. Biochem. J. 189, 615–623.CrossRefGoogle ScholarPubMed
Gutteridge, S., Tanner, S. J. & Bray, R. C. (1978 a), The molybdenum centre of native xanthine oxidase: evidence for proton transfer from substrates to the centre and for existence of an anion-binding site. Biochem. J. 175, 869–878.CrossRefGoogle Scholar
Gutteridge, S., Tanner, S. J. & Bray, R. C. (1978 b). Comparison of the molybdenum centres of native and desulpho xanthine oxidase: the nature of the cyanide-labile sulphur atom and the nature of the proton-accepting group. Biochem. J. 175, 887–897.CrossRefGoogle ScholarPubMed
Hanson, G. R., Brunette, A. A., McDonell, A. C., Murray, K. S. & Wedd, A. G. (1981). Electronic properties of thiolate compounds of oxo molybdenum(v) and their tungsten and selenium analogues. Effects of 17O, 95Mo and 95Mo isotope substitution upon ESR spectra. J. Am. chem. Soc. 103, 1953–1959.CrossRefGoogle Scholar
Harlan, E. W., Berg, J. M. & Holm, R. H. (1986). Thermodynamic fitness of molybdenum(iv, vi) complexes for oxygen atom transfer reactions, including those with enzymatic substrates. J. Am. chem. Soc. 108, 6992–7000.CrossRefGoogle Scholar
Hawkes, T. R., & Bray, R. C. (1984 a). Quantitative transfer of the molybdenum, cofactor from xanthine oxidase and from sulphite oxidase to the deficient enzyme of the nit-i mutant of Neuorospora crassa to yield active nitrate reductase. Biochem. J. 219, 481–493.CrossRefGoogle Scholar
Hawkes, T. R. & Bray, R. C. (1984 b). Studies by electron-paramagnetic-resonance spectroscopy of the environment of the metal in the molybdenum cofactor of molybdenum-containing enzymes. Biochem. J. 222, 587–600.CrossRefGoogle ScholarPubMed
Hawkes, T. R., George, G. N. & Bray, R. C. (1984). The structure of the inhibitory complex of alloxanthine (1H-pyrazolo-[3, 4 –α]pyridine-4, 6-diol) with the molybdenum centre of xanthine oxidase from electron paramagnetic resonance spectroscopy. Biochem. J. 218, 961–968.CrossRefGoogle Scholar
Hille, R. & Sprecher, H. (1987). Evidence in support of an oxo transfer mechanism in the molybdenum-containing hydroxylases. J. biol. Chem. 262, 10914–10917.CrossRefGoogle ScholarPubMed
Hinton, S. M. & Freyer, G. (1986). Cloning, expression and sequencing the molybdenum-pterin binding protein (mop) gene of Clostridium pasteurianum in Escherichia coli. Nucl. Acids. Res. 14, 9371–9380.CrossRefGoogle ScholarPubMed
Holm, R. H. & Berg, J. M. (1986). Towards functional models of metalloenzyme active sites: analogue reaction systems of the molybdenum oxo transferases. Acct. chem. Res 19. 363–370.CrossRefGoogle Scholar
Johnson, J. L. & Rajagopalan, K. V. (1977). Tryptic cleavage of rat liver sulfite oxidase; isolation and characterization of molybdenum and heme domains. J. biol. Chem. 252, 2017–2025.CrossRefGoogle ScholarPubMed
Johnson, J. L. & Rajagopalan, K. V. (1982). Structural and metabolic relationship between the molybdenum cofactor and urothione.Proc. Nat. Acad. Sci. U.S.A. 79, 6856–6860.CrossRefGoogle Scholar
Johnson, J. L., Hainline, B. E. & Rajagopalan, K. V. (1980). Characterization of the molybdenum cofactor of sulfite oxidase, xanthine oxidase, and nitrate reductase; identification of a pteridine as a structural component. J. biol. Chem. 255, 1783–1786.CrossRefGoogle ScholarPubMed
Johnson, J. L., Hainline, B. E., Rajagopalan, K. V. & Arison, B. H. (1984), The pterin component of the molybdenum cofactor; structural characterization of two fluorescent derivatives. J. biol. Chem 259, 5414–5422.CrossRefGoogle ScholarPubMed
Johnson, M. D. & Murmann, R. K. (1983). Isotopic 18O exchange between VO2+(aq) and water. Inorg. Chem 22, 1068–1072.CrossRefGoogle Scholar
Kaul, B. B., Enemark, J. M., Merbs, S. L. & Spence, J. I. (1985), Molybdenum(vi)- dioxo, molybdenum(v)-oxo, and molybdenum(iv)-oxo complexes with 2, 3:8, 9-dibenzo-1, 4, 7, 10-tetrathiadecane. Models for the molybdenum-binding site of the molybdenum cofactor. J. Am. chem. Soc. 107, 2885–2891.CrossRefGoogle Scholar
Kent, T. A., Emptage, M. H., Merkle, H., Kennedy, M. C., Beinert, H., & Münck, E. (1985). Mössbauer studies of aconitase; substrate and inhibitor binding, reaction intermediates and hyperfine interactions of reduced 3Fe and 4Fe clusters. J. Biol. Chem. 260, 6871–6881.CrossRefGoogle ScholarPubMed
Keith, T. S., Riley, M. A., Kreitman, M., Lewontin, R. C., Curtis, D. & Chambers, G. (1987). Sequence of the structural gene for xanthine dehydrogenase (rosy locus) in Drosophila melanogaster. Genetics 116, 67–73.CrossRefGoogle ScholarPubMed
Krüger, B. & Meyer, O. (1986). The pterin (bactopterin) of carbon monoxide dehydrogenase from Pseudomonas carboxydoflava. Eur.J. Biochem. 157, 121–128.Google Scholar
Lowe, D. J. (1978). Electron paramagnetic resonance in biochemistry: computer simulation of spectra from frozen aqueous samples. Biochem. J. 171, 649–651.CrossRefGoogle ScholarPubMed
Lowe, D. J., Barber, M. J., Pawlik, R. T. & Bray, R. C. (1976). A new non-functional form of milk xanthine oxidase containing quinquivalent molybdenum. Biochem. J. 155, 81–85.CrossRefGoogle ScholarPubMed
Malthouse, J. P., George, G. N., Lowe, D. J. & Bray, R. C. (1982 a), Coupling of [33S]sulphur to molybdenum(v) in different reduced forms of xanthine oxidase. Biochem. J. 199, 629–637.CrossRefGoogle Scholar
Malthouse, J. P., Williams, J. W. & Bray, R. C. (1981 b). Molybdenum(v) e.p.r. signals obtained from xanthine oxidase on reduction with aldehyde substrates and with 2-amino-4-hydroxy-6-formylpteridine. Biochem. J. 197, 421–425.CrossRefGoogle ScholarPubMed
Marcus, R. A. & Sutin, N. (1985). Electron transfers in chemistry and biology. Biochim. biophys. Ada. 811, 265–322.CrossRefGoogle Scholar
Massey, V. & Edmondson, D. (1971). On the mechanism of inactivation of xanthine oxidase by cyanide. J. biol. Chem. 245, 6595–6598.CrossRefGoogle Scholar
Meriwether, L. S., Marzluff, W. F. & Hodgson, W. G. (1966). Molybenum-thiol complexes as models for molybdenum bound in enzymes. Nature, Lond. 212, 465–467.CrossRefGoogle ScholarPubMed
Morpeth, F. F. & Bray, R. C. (1984). Inhibition of xanthine oxidase by various aldehydes. Biochemistry. 23, 1332–1338.CrossRefGoogle ScholarPubMed
Morpeth, F. F., George, G. N. & Bray, R. C. (1984). Formamide as a substrate of xanthine oxidase. Biochem. J. 220, 235–242.CrossRefGoogle ScholarPubMed
Murmann, R. K. (1980). Studies on the rates of isotopic oxygen exchange between aquated molybdenum(v) and solvent water. Inorg. Chem. 19, 1765–1770.CrossRefGoogle Scholar
Nishino, T., Nishino, T. & Tsushima, K. (1981). Purification of highly active milk xanthine oxidase by affinity chromatography on Sepharose 4B/folate gel. FEBS Lett. 131, 369–372.CrossRefGoogle ScholarPubMed
Olson, J. S., Ballou, D., Palmer, G. & Massey, V. (1974). The mechanism of action of xanthine oxidase. J. biol. Chem. 249, 4363–4382.CrossRefGoogle ScholarPubMed
Oltmann, L. F., Claassen, V. P., Kastelein, P., Reijnders, W. N. M. & Stouthamer, A. H. (1979). Influence of tungstate on the formation and activities of four reductases in Proteus mirabilis. FEBS Lett. 106, 43–46.CrossRefGoogle ScholarPubMed
Pariyadath, N., Newton, W. E. & Stiefel, E. I. (1976). Monomeric molybdenum(v) coupling showing hydrogen-1, hydrogen-2 and nitrogen-14 superhyperfine splitting in their electron paramagnetic resonance spectra: Implications for molydenum enzymes. J. Am. chem. Soc. 98, 5388–5390.CrossRefGoogle Scholar
Peterson, J., Godfrey, G., Thomson, A. J., George, G. N. & Bray, R. C. (1986). Detection by low-temperature magnetic circular-dichroism spectroscopy of optical absorption bands due to molybdenum(v) in the form of xanthine oxidase giving the Desulpho Inhibited e.p.r. signal. Biochem. J. 233, 107–110.CrossRefGoogle ScholarPubMed
Pick, F. M., McGartoll, M. A. & Bray, R. C. (1971). Reaction of formaldehyde and of methanol with xanthine oxidase. Eur. J. Biochem. 18, 65–72.CrossRefGoogle ScholarPubMed
Rajagopalan, K. V., Kramer, S. & Gardlik, S. (1986). Studies on the oxidation state of molybopterin. Polyhedron 5, 573–576.CrossRefGoogle Scholar
Rappé, A. K. & Goddard, W. A. (1982). Hydrocarbon oxidation by high-valent group 6 oxides. J. Am. chem. Soc. 104, 3287–3294.CrossRefGoogle Scholar
Rodrigues, C. G., Farchione, F., Hanson, G. R., Wilson, G. L., O'Connor, M. J. & Wedd, A. G. (1985). Xanthine oxidase: (1) interpretation of 17O-hyperfine coupling parameters: (2) Crystallization experiments.Climax 5th Internat. Conf. on Chemistry and Uses of Molybdenum, Newcastle, UK, Abstracts 55–56.Google Scholar
Rodgers, K. R., Murmann, R. K., Schlamper, E. O. & Shelton, M. C. (1985). Rates of isotopic oxygen exchange with solvent and oxygen atom transfer involving [Mo3O4(OH2)9]4+. Inorg. Chem. 24, 1313–1322.CrossRefGoogle Scholar
Scott, R. A. (1984). X-ray absorption spectroscopy. In Structural and Resonance Techniques in Biological Research (ed. Rousseau, D. L.), pp. 295–362. Orlando, Florida: Academic Press.CrossRefGoogle Scholar
Scullane, M. I., Taylor, R. D., Minelli, M., Spence, J. T., Yamanouchi, K., Enemark, J. H. & Casteen, N. D. (1979). Electron paramagnetic resonance – structural studies of molybdenum(v)–oxo complexes. Inorg. Chem. 18 3213–3219.CrossRefGoogle Scholar
Shilov, A. E. (1987). J. Molecular Catalysis 41, 221–234.CrossRefGoogle Scholar
Skibo, E. B., Gilchrist, J. H. & Lee, C-H. (1987). Electronic probes of the mechanism of substrate oxidation by buttermilk xanthine oxidase: role of the active site nucleophile in oxidation. Biochemistry 26, 3032–3037.CrossRefGoogle ScholarPubMed
Smith, B. E.Campbell, F., Eady, R. R., Eldridge, M., Ford, C. M., Hill, S., Kavanagh, E. P., Lowe, D. J., Miller, R. W., Richardson, T. H., Robson, R. L., Thorneley, R. N. F. & Yates, M. G. (1987). The biochemistry of nitrogenase and the physiology of related metabolism. Phil. Trans. R. Soc. Lond. B317, 131–146.Google Scholar
Solomonson, L. P., Barber, M. J., Howard, D. W., Johnson, J. L. & Rajagopalan, K. V. (1984). Electron paramagnetic resonance studies on the molybdenum center of assimilatory NADH: nitrate reductase from Chlorella vulgaris. J. biol. Chem. 259, 849–853.CrossRefGoogle ScholarPubMed
Spiro, T. G. (1985). Molybdenum Enzymes. New York: Wiley Interscience.Google Scholar
Stephens, P. J. (1985). The structures of the iron-molybenum and the iron proteins of the nitrogenase enzyme. In Molybdenum Enzymes (ed. Spiro, T. G.), pp. 117–159. New York: Wiley Interscience.Google Scholar
Stiefel, E. I. & Cramer, S. P. (1985). Chemistry and biology of the iron-molybdenum cofactor of nitrogenase. In Molybdenum Enzymes (ed. Spiro, T. G.), pp. 89–116. New York: Wiley Interscience.Google Scholar
Tanner, S. J., Bray, R. C. & Bergmann, F. (1978). 13C Hyperfine splitting of some molybdenum electron-paramagnetic resonance signals from xanthine oxidase. Biochem. Soc. Trans. 6, 1328–1330.CrossRefGoogle ScholarPubMed
Tullius, T. D., Kurtz, D. M., Conradson, S. D. & Hodgson, K. O. (1979). The molybdenum site of xanthine oxidase. Structural evidence from X-ray absorption spectroscopy. J. Am. chem. Soc. 101, 2776–2779CrossRefGoogle Scholar
Turner, N., Barata, B., Bray, R. C., Deistung, J., Le Gall, J. & Moura, J. J. G. (1987). The molybdenum iron-sulphur protein from Desulfovibrio gigas as a form of aldehyde oxidase. Biochem. J. 243, 755–761.CrossRefGoogle ScholarPubMed
Vincent, S. P. & Bray, R. C. (1978). Electron-paramagnetic-resonance studies on nitrate reductase from Escherichia coli K12. Biochem. J. 171, 639–647.CrossRefGoogle ScholarPubMed
Wagner, R., Cammack, R. & Andreesen, J. R. (1984). Purification and characterization of xanthine dehydrogenase from Clostridium acidiurici grown in the presence of selenium. Biochem. biophys. Ada 791, 63–74.Google Scholar
Weiner, J. H. (1987) (unpublished work).Google Scholar
Williams, J. W., Rinderle, S. J., Schrier, J. A., Alvey, L. J. & Tseng, K. (1986). Arsenite oxidase: a molybdenum-containing iron–sulphur protein. Fed. Proc. 45, 1660.Google Scholar
Williams, R. J. P. & Wentworth, R. A. D. (1974). Molybdenum in enzymes. In Chemistry and Uses of Molybdenum (ed. Mitchell, P. C. H.), pp. 212–215. London: Climax Molybdenum Company.Google Scholar
Yamamoto, I., Okubo, N. & Ishimoto, M. (1986). Further characterization of the trimethylamine N-oxide reductase from Escherichia coli, a molybdoprotein. J. Biochem. (Tokyo) 99, 1773–1779.CrossRefGoogle ScholarPubMed
Yamase, T., Sasaki, R. & Ikawa, I. (1981). Photochemical studies of the alkylammonium molybdates. Part 5. Photolysis in weak acid solutions J. chem. Soc., Dalton 628–634.CrossRefGoogle Scholar
Young, C. G., Enemark, J. H., Collison, D. & Mabbs, F. E. (1987). The first mononuclear Mo(v) complex with a terminal sulfido group: [HB(Me2C3N2H)3] MoSCl2. Inorg. Chem. 26, 2925–2927.CrossRefGoogle Scholar