We describe a convenient, simple and novel continuous spectrophotometric method for the determination of aminoacyl-tRNA synthetase activity. The assay relies upon the measurement of inorganic pyrophosphate generated in the first step of the aminoacylation of a tRNA. Pyrophosphate release is coupled to inorganic pyrophosphatase, to generate phosphate, which in turn is used as the substrate of pu...

A continuous spectrophotometric assay based on the differences in the ultraviolet spectra of trans-stilbene oxide (TSO) and its reaction product 1,2-diphenyl-1,2-ethanediol is described for the measurement of mammalian cytosolic epoxide hydrolase activity. Rates of TSO hydration determined by this method were similar to those obtained by independent analytical methods, and the assay is rapid, r...

A spectrophotometric assay of proteolytic enzyme activity is described in which the optical density obtained by a given enzyme preparation is related (2 alpha less than 0.01) to the serological activity of that preparation in a two stage technique. The assay appears to be of use for the standardisation of enzyme preparations for use in blood group serology.

A simple and sensitive spectrophotometric assay for quaternary ammonium compounds (QACs) based on Dragendorff's reagent is described. Although not specific for a particular QAC, the assay allows for rapid survey of tissue for QAC content. A separation method for QACs in halophyte tissue containing high levels of cations was developed using ion exchange resins and ninhydrin to remove the amino a...

BACKGROUND Salivary alpha-amylase (sAA) is considered a biomarker of sympathetic activation in humans, but there is controversy regarding the existence of sAA in dogs. The hypothesis of this study was that sAA exists in dogs and it could change in situations of sympathetic stimulation. Therefore, the aims of this study were: 1) to demonstrate the presence of alpha-amylase in saliva of dogs by W...