The copper-molybdenum antagonism in ruminants. I. The formation of thiomolybdates in animal rumen

Clarke, Nicholas J.; Laurie, Stuart H.

doi:10.1016/s0162-0134(00)80041-0

Cited by 49 publications

(26 citation statements)

References 11 publications

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“…Molybdenum-sulfur complexes, like ATM, are very potent anti-copper agents [21,22]. Copper is an important co-factor for several enzymes controlling numerous necessary processes including endothelial cell division (e. g. Copper/Zinc superoxide dismutase and ceruloplasmin) [17,23].…”

Section: Discussionmentioning

confidence: 99%

Effects of ammonium tetrathiomolybdate, an oncolytic/angiolytic drug on the viability and proliferation of endothelial and tumor cells

et al. 2007

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Section: Discussionmentioning

confidence: 99%

Effects of ammonium tetrathiomolybdate, an oncolytic/angiolytic drug on the viability and proliferation of endothelial and tumor cells

et al. 2007

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“…(1 984). Clarke & Laurie (1980) showed that in pure aqueous solutions TTM formation only occurred at su1phide:Mo values of 10: 1. However, Bray et al.…”

Section: Discussionmentioning

confidence: 99%

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

Allen

Gawthorne

1987

Br J Nutr

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1. Merino sheep fed on a diet of chopped wheaten hay, chopped lucerne (Medicago saliva) hay and oat grain were the source of rumen contents for the study. The diet contained (mg/kg dry weight) 3.3 copper, 024 molybdenum and 2-8 sulphur. The effects of adding between 5 and 25 mg Mo/kg as ammonium molybdate (AM) or tetrathiomolybdate (TTM) on the distribution and forms of Cu and Mo in rumen contents were investigated in vivo and in vitro. 2.Approximately 88 YO of the Cu and 94% of the Mo in rumen contents were associated with the solid phase.When AM or TTM was added to rumen contents in vivo or in vitro the proportion of these elements in the solid phase was increased at the expense of the fluid phase.3. The addition of AM and TTM to rumen contents also decreased the proportion of Cu that was soluble in trichloroacetic acid (50 g/l ; TCA) and increased the proportion of Cu that was not extractable by sequential treatment with TCA and neutral detergent.4. Column chromatography of neutral-detergent extracts of rumen contents revealed that TTM treatment caused Cu to be strongly bound to proteins of high molecular weight.5. Addition of sulphide to rumen contents did not result in significant changes in the distribution of Cu between the fluid and solid phases, or in the solubility of Cu in TCA.6. It is postulated that constant removal of TTM from the fluid phase via reaction with proteins and other macromolecules in the solid phase results in greater formation of TTM in vivo than would be expected from solution chemistry. The molybdo-proteins so formed are strong chelators of Cu and may be the agents responsible for the decrease in Cu absorption in animals that consume diets containing high concentrations of Mo.When relatively high concentrations of molybdenum and sulphur are simultaneously present in the diet of ruminants the availability of copper to the animal is seriously compromised (Dick, 1956). The production of thiomolybdates in the rumen, and the subsequent decrease in the availability of Cu due to the formation of insoluble Cu thiomolybdates has been suggested as a hypothesis for the interaction (Dick et al. 1975). Confirmation of the hypothesis via spectrophotometric evidence of the presence of these compounds in rumen contents has been hampered by interference from other compounds, and by the low concentrations of Mo normally present. However, at moderately high molybdate concentrations, absorption spectra typical of thiomolybdates have been found in washed suspensions of rumen micro-organisms (Dick et al. 1975;El Gallad et al. 1983), in an artificial rumen apparatus (Bray et al. 1982), and in whole rumen contents (El Gallad et al. 1983), thereby indicating that the potential for thiomolybdate formation does exist .Interest has also centred on the particular species of thiomolybdates that may occur in vivo. Based on observations of solution chemistry, Clarke 8z Laurie (1980) concluded that tetrathiomolybdate (TTM) would not form unless the sulphide : Mo ratio was very high, and that at the lower ratios mor...

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“…Using non-fermentation ruminal conditions, Clarke & Laurie ( 8 ) showed the formation of the relative thiomolybdates to be pH- and S (given as sulfide):Mo molar ratio-dependent. Clarke & Laurie ( 8 ) showed at pH 7·0 that molar S:Mo ratios of < 3 only produced mono-thiomolybdates, 5–10:1 resulted in di-thiomolybdates, above 10 quickly transformed to tri-thiomolybdates, but found total conversion to tetra-thiomolybdate occurring at about 300:1. An S:Mo molar ratio of 62:1 at pH 8·0 resulted in the di-thiomolybdate being the predominant form (with no significant tetra-thiomolybdate), whereas at pH 6·5 the tri form dominated, and as pH decreased the tetra-thiomolybdate form increased.…”

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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The copper-molybdenum antagonism in ruminants. I. The formation of thiomolybdates in animal rumen

Cited by 49 publications

References 11 publications

Effects of ammonium tetrathiomolybdate, an oncolytic/angiolytic drug on the viability and proliferation of endothelial and tumor cells

Effects of ammonium tetrathiomolybdate, an oncolytic/angiolytic drug on the viability and proliferation of endothelial and tumor cells

Involvement of the solid phase of rumen digesta in the interaction between copper, molybdenum and sulphur in sheep

Role of the rumen in copper and thiomolybdate absorption

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