Thiomolybdates in rumen contents and rumen cultures

El-Gallad, T.T.; Mills, Colin F.; Bremner, I.; Summers, Ryan M.

doi:10.1016/0162-0134(83)85047-8

Cited by 17 publications

(10 citation statements)

References 7 publications

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“…Although the thiomolybdate anions are watersoluble, they must be largely associated with the particulate matter in ruminant digesta if they are to account for the loss of availability of Cu seen in the present experiments. It is therefore interesting to note that MoSi-, when added in solution to rumen contents, rapidly disappears from the aqueous phase (El-Gallad et al 1983). The results of the present study would suggest that while the availability of Cu given to the rat simultaneously with MoSiin the molar ratio, 2 Cu: 1 Mo (i.e.…”

Section: Discussionmentioning

confidence: 72%

A new bioassay for assessment of copper availability and its application in a study of the effect of molybdenum on the distribution of available Cu in ruminant digesta

Price¹,

Chesters²

1985

Br J Nutr

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1. Investigations were carried out on the feasibility of using an oral repletion technique in the rat to assess the bioavailability of copper in experimental sources providing no more than 250 μg Cu from any one source.2. Preliminary studies on the response in plasma Cu ofpartially Cu-depleted rats given repletion doses of 20–50 μg Cu as CuSO4/d on four consecutive days indicated that this index of Cu status was insufficiently sensitive to Cu dose.3. Incontrast, theactivityofcytochromecoxidase(EC 1. 9.3.1)in theduodenalmucosa ofpartiallycu-depleted rats showed a measurable and uniform response to 10 μg Cu as CuSO4/d given on three consecutive days. Furthermore, when the rats were given 0, 2.5, 5.0 or 10.0 μg Cu/d, the increase in cytochrome c oxidase activity above that of the unsupplemented control group was linearly related to Cu dose. The mean response in cytochrome c oxidase activity in groups of eight rats was therefore used to assess the availability of Cu from experimental sources relative to that of Cu as CuSO4, only 240 μg Cu being required from each experimental material.4. The assay was used to study the effect of the Cu-antagonist molybdenum on the distribution of available Cu in digesta from sheep given dried grass either untreated (1.6 mg Mo/kg dry matter (DM)) or treated with ammonium molybdate (11.6 mg Mo/kg DM).5. The relative availability of Cu in untreated dried grass (75%) was substantially higher than in rumen (12%), duodenal (43%) or ileal (28%) digesta. In all cases, addition of Mo to the diet resulted in a substantial reduction in Cu availability.6. The effects of Mo on availabilitv of Cu are discussed with suecial reference to the Dossible involvement of thiomolybdates in the Cu-Mo antagonism.

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Section: Discussionmentioning

confidence: 72%

A new bioassay for assessment of copper availability and its application in a study of the effect of molybdenum on the distribution of available Cu in ruminant digesta

Price¹,

Chesters²

1985

Br J Nutr

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“…[39] Our own studies [40,41] have confirmed that a rapid reaction occurs between Cu II ions and its complexes with TTM and with the oxythiomolybdates: in fact, taking into account the rapidity of the reaction and the rumen concentrations it was concluded that the oxythiomolybdate ions MoO x S xϪ4 2Ϫ (x ϭ 1,2) were the more likely reactants. [41] Studies by Mason and co-workers show that the di-, tri-, and tetrathiomolybdates all have an effect on Cu metabolism when given intravenously to ruminants and have a reversible inhibitory effect on caeruloplasmin oxidase.…”

Section: Biological Properties the Copper؊molybdenum Antagonismmentioning

confidence: 84%

“…[36Ϫ38] Mills and his co-workers subsequently showed that TTM forms from molybdate ion in rumen cultures. [39] Laboratory simulation of rumen conditions also showed that the oxythiomolybdate ions and subsequently TTM can form. [40] However, because of the low natural concentrations of molybdate in the rumen it has not been possible to directly observe the presence of any thiomolybdate within a rumen.…”

Section: Biological Properties the Copper؊molybdenum Antagonismmentioning

confidence: 98%

Thiomolybdates — Simple but Very Versatile Reagents

Laurie

2000

Eur. J. Inorg. Chem.

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A large number of thiometallate anions, MOxS4−xn−, and some of the seleno analogues, are known in which M is a transition metal in a high oxidation state. They are characterised by their strong colours arising from low energy S(Se)→M charge transfer transitions, by unusual redox properties and by their ability to act as ligands to produce a wide range of heterometal complexes. This review outlines some of these properties associated with the thiometallate anions of molybdenum(VI). These anions are prepared by passing H2S through an alkaline molybdate solution, giving a sequential replacement of O atoms by S and ultimately MoS42− (TTM) as product. The thiomolybdates, particularly TTM, have been the most intensively studied because of their ease of preparation, their relatively greater thermal and hydrolytic stabilities and their biological roles. Unusual redox changes which involve internal electron transfer have been shown by reaction with organic disulfides and with CuII. In the latter case insoluble polymeric products are readily formed which, from EPR and EXAFS studies, involve S‐bridged reduced Cu and Mo centres. Reaction of TTM with CuI, on the other hand, produces a range of complexes in which from 1 to 6 Cu ions add across the tetrahedral faces of TTM with no redox changes. Further CuI ions can be added to the [Cu6(MoS4)] moiety to produce cluster ions. This illustrates the ability of the thiometallates to act as building blocks for a very wide range of heterometal complexes ranging from simple linear ions to complex clusters, a prime example of the latter being the FeMo cofactor of the enzyme nitrogenase. TTM was identified sometime ago as the reactive intermediate in the Mo‐induced Cu‐deficiency that afflicts ruminants with serious consequences. Subsequently TTM, as its ammonium salt, has been successfully used in removing the excess Cu and then controlling the Cu levels of patients of Wilson’s disease. It appears to act by blocking the intestinal absorption of Cu and by converting Cu into a metabolically inert form, and in these respects is different to the mode of action of chelating agents which can be used for treating this disease.

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“…Incubations of sieved (through a 0·9 × 0·9 mm muslin mesh) rumen fluid (from cattle fed no Mo) with molybdate (0·1 m m ) and sulfate (2·4 m m ) by Elgallad et al ( 10 ) resulted in the production of an absorption spectra indicative of tetra-thiomolybdate (239, 317 and 467 nm) with no peaks indicative of di- or tri-thiomolybdates (392 and 394 nm), indicating that only tetra-thiomolybdate was produced in significant amounts. However, when Cu was added to the culture before the incubation there was no evidence of tetra-thiomolybdates in the rumen fluid culture.…”

Section: Are Thiomolybdates Produced In the Rumen?mentioning

confidence: 99%

“…However, when Cu was added to the culture before the incubation there was no evidence of tetra-thiomolybdates in the rumen fluid culture. Transferring their work into the whole animal, Elgallad et al ( 10 ) showed that in cattle fed 100 mg Mo per kg DM, 3 g S per kg DM and 200 mg Cu per kg DM, there was no TCA-insoluble Cu and little albumin-bound Cu. However, when Cu was reduced to 1 mg/kg DM the TCA-insoluble Cu content increased and greater than 80 % of this was associated with albumin, Mo and Cu; the caeruloplasmin concentrations were also reduced.…”

Section: Are Thiomolybdates Produced In the Rumen?mentioning

confidence: 99%

Role of the rumen in copper and thiomolybdate absorption

Gould

Kendall

2011

Nutr. Res. Rev.

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The rumen is the site of significant interactions between Cu, S and Mo. It also shows reactions between Cu, S and Fe. The interaction between Mo and S results in the formation of thiomolybdates, which in the absence of adequate quantities of rumen Cu are absorbed into the animal and bind to Cu in biological compounds. This is the cause of thiomolybdate toxicity, often misleadingly called Cu deficiency. The effects of thiomolybdates being absorbed into the animal are considered, especially how thiomolybdates bind to Cu-containing compounds such as enzymes, decreasing their activity without removing the active Cu component. The sources of Cu, Mo, Fe and S are examined, including the impacts of water and soil on the animal's intake. Within the present review we have been able to provide evidence that: all classes of thiomolybdates are formed in the rumen; in the absence of available Cu all thiomolybdates can be absorbed into the animal rapidly though the rumen wall or via the small intestine; thiomolybdates bind to Cu in biological compounds and are able to cause problems; effects of thiomolybdate are reversible in vivo and in vitro on cessation of thiomolybdate challenge; the tetra-thiomolybdate form is the most potent Cu binder with decreased potency with decreasing S in the compound. Fe will exacerbate a thiomolybdate problem but will not directly cause it.

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Thiomolybdates in rumen contents and rumen cultures

Cited by 17 publications

References 7 publications

A new bioassay for assessment of copper availability and its application in a study of the effect of molybdenum on the distribution of available Cu in ruminant digesta

A new bioassay for assessment of copper availability and its application in a study of the effect of molybdenum on the distribution of available Cu in ruminant digesta

Thiomolybdates — Simple but Very Versatile Reagents

Role of the rumen in copper and thiomolybdate absorption

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