Molybdenum-containing enzymes

Bray, R. C.; Swann, John C.

doi:10.1007/bfb0002461

Cited by 113 publications

(43 citation statements)

References 88 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This means that the signal is not related to reperfusion injury. The apparent g-values together with the observed slow relaxation is reminiscent of molybdenum [42,43]. Since the high field line of this centre, at g = 1.985, was also encountered in this study in mitochondria, we surveyed the literature for more data.…”

Section: Discussionmentioning

confidence: 84%

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

Kraaij

Koster

Hagen

1989

Biochemical Journal

View full text Add to dashboard Cite

The present study was designed to measure directly, using e.p.r. spectroscopy, oxygen-derived free radicals in (post)-ischaemic or (post)-anoxic rat hearts. Rat hearts were rapidly freeze-clamped at 77 K under normoxic, anoxic, ischaemic or reperfusion conditions. The samples were measured at three different temperatures (13, 77 and 115 K) and at several microwave power levels, and were compared with isolated rat heart mitochondria. Samples were prepared both by grinding and as tissue cuts. The two preparation techniques gave identical e.p.r. results, which excludes the occurrence of grinding artifacts. No free radical signals linked to reperfusion injury were detected. Several electron transfer centres known in the mitochondrial respiratory chain were measured. The signals previously assigned to post-ischaemic reperfusion injury were found to originate from electron transfer centres of the respiratory chain, predominantly the iron-sulphur cluster S-1 in succinate dehydrogenase. The differences in signal intensity between normoxic, ischaemic and reperfused hearts were found to result from the different redox stages of these centres under the various conditions tested. These findings do not necessarily imply that oxygenderived free radicals are not formed in cardiac tissue during (post)-ischaemic reperfusion. The constitutive background of paramagnetism from the respiratory chain, however, seriously hampers the direct detection of comparatively low concentrations of free radicals in cardiac tissue. It is therefore expedient to focus future experiments in this field on the use of spin-trapping agents.

show abstract

Section: Discussionmentioning

confidence: 84%

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

Kraaij

Koster

Hagen

1989

Biochemical Journal

View full text Add to dashboard Cite

show abstract

“…From earlier studies it is not clear that biological molybdenum and FAD are even near each other (12), except possibly during a turnover of the enzyme molecule, and so we recognize that this study may or may not have any relevance to the biological systems. In any case the study has revealed some new and interesting chemistry of both molybdenum and of the derivative of riboflavin which we employed as a model of FAD.…”

Section: Introductionmentioning

confidence: 88%

“…Inasmuch as molybdenum and a flavine (FAD in particular) are essential co-factors in several enzyme systems (12), and since neither X-ray nor any kind of solution studies have established the ligand binding sites of flavines on molybdenum, we decided to undertake a detailed 'H nrnr study of solutions of a particular molybdenum-flavine system. From earlier studies it is not clear that biological molybdenum and FAD are even near each other (12), except possibly during a turnover of the enzyme molecule, and so we recognize that this study may or may not have any relevance to the biological systems.…”

Section: Introductionmentioning

confidence: 99%

sHigh resolution ¹H nuclear magnetic resonance studies of a flavine and its product with MoCl₄

Roberie¹,

Bhacca²,

Selbin³

1977

Can. J. Chem.

View full text Add to dashboard Cite

The high resolution 1H nmr spectra of the substituted flavine, 3-N-methyltetraacetylriboflavine (3-Me-TARF), and its non-aqueous solution complexes with Gd(fod)3, Eu(fod)3, MoCl4, and MoCl4•2CH3(CH2)2CN, were studied in order to try to discern the binding sites of the flavine as it attaches to the molybdenum. Evidence was found that all three metal atoms, Gd(III), Eu(III), and Mo(IV), are attached in solution not only by the primary binding (chelating) sites of the flavine, viz., the O-4 and N-5 atoms, but also by an acetyl oxygen atom, at the C-4′ site of the ribityl side chain. 300 MHz spectra of the 3-Me-TARF have permitted the coupling constants for the side chain methine and methylene protons to be obtained.

show abstract

“…Microorganisms such as the yeast Pichia guillermondii and the bacterium Micrococcus reduced molybdenum trioxide and molybdate to molybdenum blue which is characteristic of pentavalent molybdenum complexes (110). Mo (V) EPR signals have been detected in bacteria, plant and animal tissues which contain molybdenum enzymes such as xanthine oxidase, sulfite oxidase and formate dehydrogenase (111). Rats were capable of incorporating molybdenum into liver sulfite oxidase and xanthine oxidase when injected with molybdate, however, molybdate was not able to reconstitute the apoenzymes in vitro (112).…”

Section: Enzyme Interactionmentioning

confidence: 99%

The role of metals in carcinogenesis: biochemistry and metabolism.

Jennette¹

1981

Environ Health Perspect

154

View full text Add to dashboard Cite

The oxyanions of vanadium, chromium, molybdenum, arsenic, and selenium are stable forms of these elements in high oxidation states which cross cell membranes using the normal phosphate and/or sulfate transport systems of the cell. Once inside the cell, these oxyanions may sulfuryl transfer reactions. Often the oxyanions serve as alternate enzyme substrates but form ester products which are hydrolytically unstable compared with the sulfate and phosphate esters and, therefore, decompose readily in aqueous solution. Arsenite and selenite are capable of reacting with sulfhydryl groups in proteins. Some cells are able to metabolize redox active oxyanions to forms of the elements in other stable oxidation states. Specific enzymes may be involved in the metabolic processes. The metabolites of these elements may form complexes with small molecules, proteins and nucleic acids which inhibit their ability to function properly. The divalent ions of beryllium, manganese, cobalt, nickel, cadmium, mercury, and lead are stable forms of these elements which may mimic essential divalent ions such as magnesium, calcium, iron, copper, or zinc. These ions may complex small molecules, enzymes, and nucleic acids in such a way that the normal activity of these species is altered. Free radicals may be produced in the presence of these metal ions which damage critical cellular molecules.

show abstract

Molybdenum-containing enzymes

Cited by 113 publications

References 88 publications

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

sHigh resolution ¹H nuclear magnetic resonance studies of a flavine and its product with MoCl₄

The role of metals in carcinogenesis: biochemistry and metabolism.

Contact Info

Product

Resources

About

Molybdenum-containing enzymes

Cited by 113 publications

References 88 publications

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

Reappraisal of the e.p.r. signals in (post)-ischaemic cardiac tissue

sHigh resolution 1H nuclear magnetic resonance studies of a flavine and its product with MoCl4

The role of metals in carcinogenesis: biochemistry and metabolism.

Contact Info

Product

Resources

About

sHigh resolution ¹H nuclear magnetic resonance studies of a flavine and its product with MoCl₄