Molybdenum in Biology - An Essential Trace Element
Amino acid and protein metabolism
At low concentrations molybdenum has a beneficial effect on animal growth and protein synthesis in some species. Chicks grew more rapidly and had a higher haemoglobin count when 1-5 ppm Mo was added to the diet [Humphries, 1970; Norris, 1969; Probst, 1971]. The improvement in growth did not occur with diets containing 100 ppm Mo indicating some toxicity at this higher level. Molybdenum promotes protein synthesis in the red trout [Jurca and Matei, 1967]. Trout raised on a diet which included 0.126 g ammonium molybdate/100 kg forage were larger and better developed than those raised on fresh food and the protein content of the blood serum was increased. However, according to other work molybdenum may have an inhibitory effect on protein synthesis. Molybdenum (400 ppm) added to the diet of experimental rats did not affect digestion and absorption of nitrogen compounds but caused an increase in urinary excretion first as urea and ammonia and then as alpha-amino nitrogen [Johnson and Miller, 1963; Val chuk and Kovalskaya, 1970]. Urinary levels of alpha-amino nitrogen increased with increased dietary molybdenum and with increased time of feeding, and urea and ammonia decreased. Molybdenum inhibited incorporation of leucine into protein in a homogenised rat liver preparation (16% inhibition at 10-4 M Mo and 80% inhibition at 10-3 M) [Peive, 1968].