A kinetic enzymological assay for methotrexate in serum is described; the results are available after 1.5 hours. The lower limit of sensivity is 50 nmol/1; the day-to-day variation coefficients compare favourably with other procedures (about 7% in the 200-600 nmol/1 range). The method uses purified dihydrofolic acid reductase from bovine liver. The problem of its instability in the assay is ci...

Assay cocktail modification such as addition of effector can cause inadvertent changes in the concentration of other metalligand and free species. In some cases, e.g. in the assay for phosphoenolpyruvate carboxylase under a limiting-substrate condition, unintentional changes in substrate concentration are significant and confound an interpretation based solely on the total concentration of each...

This systematic study includes physical–chemical characterisation of nanomaterials, arsenic adsorption assays, mechanism proposal, and acute toxicity assays with Daphnia magna .

Lysogenic conversion of Shigella flexneri type antigens was studied with the aid of wild-type and thermosensitive mutant phages. With all wild-type phages, the appearance of glycosylated antigen was accompanied by the appearance of polyprenyl phosphate glucose synthetase activity. With some of the mutant phages, the appearance of glycosylated antigen was not followed by the formation of lipid-l...