A simple determination of 5'-Nucleotidase in blood serum without deproteinization is described. The enzyme activity is distinguished from that of a nonspecific alkaline phosphatase by nickel inhibition and the inorganic phosphate released from adenosine monophosphate used as substrate is determined by a method previously described. Additional studies include the determination of optimal conditi...

A chronoamperometric method for vanadium ion determination, based on the inhibition of the enzyme alkaline phosphatase, is reported. Screen-printed carbon electrodes modified with gold nanoparticles were used as transducers for the immobilization of the enzyme. The enzymatic activity over 4-nitrophenyl phosphate sodium salt is affected by vanadium ions, which results in a decrease in the chrono...

a thin-layer chromatography method has been developed and evaluated for the separation and determination of lysine and methonine in a mixture of amino acids obtained from acid or enzyme hydrolysis of protein. the solvent systems were (a) ethanol-ether, (b) phenol-water, (c) ethyl methyl ketone-pyridine-distilled water-glacial acetic acid. procedures in all the three stages were in the same dime...

A novel amperometric biosensor for the determination of Al(III) based on the inhibition of the enzyme acetylcholinesterase has been developed. The immobilization of the enzyme was performed on screen-printed carbon electrodes modified with gold nanoparticles. The oxidation signal of acetylthiocholine iodide enzyme substrate was affected by the presence of Al(III) ions leading to a decrease in t...

Serum acid phosphatase was measured in patient with enlarged benign and malignant prostate before and after rectal examination. Amongst the patients with benign glands, rectal examination did not produce any significant false elevation of the enzyme. Rectal examination, however, caused a ci e in the enzyme level in a few untreated cancer patients and in cancer patients who had become refractory...

The simultaneous determination of L tyrosine and L lysine, by enzyme supported flow injection analysis (FIA) was developed using two enzyme reactors in parallel and a single oxygen electrode. L-Tyrosine and L-lysine were determined using the enzyme Ltyrosinase (EC 1.14.18.1) and L-lysineLY -oxidase (LysOD, EC 1.4.3. -), respectively. When sample solutions were simultaneously injected into the t...

A rapid, high-sensitivity, chemiluminescence (CL) enzyme assay for the determination of organophosphate (OP) residues in milk is presented. The assay for quantification of OP residues in milk is based on the inhibition of enzyme butyrylcholinesterase (BuChE). BuChE was stabilized and preloaded in 384 well plates at 30 °C. The assay permits rapid determination of OPs in milk within 12 min includ...

The effect of the reaction conditions (substrate concentration, enzyme dosage, and pH) on cyclodextrin production by cyclodextrin glucanotransferase from Bacillus megaterium was investigated by applying mathematical modeling methods. Adequate models were developed and they were used for determination of the optimal conditions for maximal formation of beta-cyclodextrins at minimal concentrations...

This amperometric technique for the determination of enzyme activity is based on detecting a decrease in the concentration of the NADH co-factor of the enzyme reaction. A glassy carbon electrode, modified by adsorption of Mg2+ and NADH, is used to measure the anodic peak current that corresponds to the oxidation of NADH. We found no significant difference between the enzyme activity of lactate ...

Nanostructured materials are a new class of enzyme mimics, the inhibitors of which have not been studied. Herein, we demonstrate the screening of inhibitors for Au@Pt nanorod (NR) oxidase mimics. In addition, based on the enzyme inhibition reaction, determination of "poisoning" inhibitors is demonstrated.