A spectrophotometric method for the detection of tyrosinase activity is developed by utilizing the product-triggered aggregation of boronic acid-functionalized gold nanoparticles. Based on the changes of absorbance in UV-visible spectra, the assay shows extremely high sensitivity and lowered limit of detection of 1 × 10(-10) u mL(-1).

We describe a modified enzymic reagent for determination of cholesterol and cholesterol ester in serum and in high-density lipoprotein. In this new procedure, the hydrogen peroxide produced by the action of cholesterol oxidase is used as a substrate for NAD+ peroxidase. Spectrophotometric determination of the NADH consumed in this coupled reaction provides a direct and absolute measure of the c...

We describe a convenient and simple continuous spectrophotometric method for the determination of mitogen-activated protein kinase (MAPK) kinase activity with its protein substrate. The assay relies on the measurement of phosphoprotein product generated in the first step of the MAPK kinase reaction. Dephosphorylation of the phosphoprotein is coupled to a MAPK phosphatase to generate phosphate, ...

Background Lytic polysaccharide monooxygenases (LPMO) release a spectrum of cleavage products from their polymeric substrates cellulose, hemicellulose, or chitin. The correct identification and quantitation of these released products is the basis of MS/HPLC-based detection methods for LPMO activity. The duration, effort, and intricate analysis allow only specialized laboratories to measure LPMO...

When dhurrin [p-hydroxy-(S)-mandelonitrile-tJ-D-glucoside], the cyanogenic glucoside of sorghum [Sorghum bicolor (L.) Moench], is hydrolyzed by autoclaving, p-hydroxybenzaldehyde (P-HB) is released. The spectrophotometric determination of pHB concentration in autoclaved sorghum leaf extracts provides a measure of the hydrocyanic acid potential (HCN-p) of leaf tissue. Extracts of field-grown sor...

The study included analysis of five different brands Paracetamol tablets used in market, using the ultra violet spectro-photometric method. percent purity was determined by assay method on uv spectrophotometer. result obtained compared with those standard. Percent content standard IP contain no less than 95.0 and not more 105.0 prescribed value. It noted that samples A, B, D E meet I.P. specifi...

We evaluated four spectrophotometric methods for suitability in determining total protein in human milk samples. Results were compared with those by an established method for the determination of total nitrogen (micro-Kjeldahl). Values for total protein by all four methods significantly correlated with micro-Kjeldahl. For the biuret assay, Lowry-Peterson assay, Bio-Rad Coomassie Blue assay, and...

An automatic enzyme kinetic luminometric method for determination of small quantities of urea in biological fluids and in microdialysates is presented. The method is based on the ATP-hydrolyzing urease reaction [urea amidohydrolase (ATP-hydrolyzing); EC 3.5.1.45], monitored by a luciferin-luciferase ATP reaction. The assay range is 100 pmol to 50 nmol with a detection limit of 5 micromol/L in t...

A rapid method for determining the presence of barbiturate in serum has been needed for some time. Presently used methods are all relatively time-consuming. A rapid immunoassay for the detection of barbiturate in urine, the “Enzyme Multiplied Immunoassay Technique” (EMIT), has recently become available. We have compared results of the EMIT urine assay with results of a spectrophotometric assay ...

In this study, we determined the in vitro inhibitory effects of ceftriaxone sodium, imipenem and ornidazole on hydratase and esterase activities of human erythrocyte carbonic anhydrase-I and II isozymes (CA I and II). Human erythrocyte CAI and II isozymes were purified by Sepharose-4B L-tyrosine affinity chromatography column with a yield of 30% and 40%, a specific activity of 920 and 8,000 EU/...