Non-toxic total nitrogen determination using a low alkaline persulfate digestion.

Measuring total nitrogen, nitrate, and nitrite is critical for compliance with water safety standards. Previous methods for measuring total nitrogen were hazardous, time consuming, and expensive. Here we report a method for measuring total nitrogen in water and soil using alkaline persulfate digestion combined with a Nitrate Reductase assay.

Bioelectrocatalytic and electrochemical cascade for phosphate sensing with up to 6 electrons per analyte molecule.

Despite the availability of numerous electroanalytical methods for phosphate quantification, practical implementation in point-of-use sensing remains virtually nonexistent because of interferences from sample matrices or from atmospheric O. In this work, phosphate determination is achieved by the purine nucleoside phosphorylase (PNP) catalyzed reaction of inosine and phosphate to produce hypoxanthine which is subsequently oxidized by xanthine oxidase (XOx), first to xanthine and then to uric acid. Both PNP and XOx are integrated in a redox active Os-complex modified polymer, which not only acts as supporting matrix for the bienzymatic system but also shuttles electrons from the hypoxanthine oxidation reaction to the electrode.

Affinity binding via zinc(II) for controlled orientation and electrochemistry of histidine-tagged nitrate reductase in self-assembled monolayers.

Monolayers of Cu(II)-complexes on electrode surfaces are frequently applied for the immobilization and controlled orientation of His-tagged redox proteins. However, affinity binding is limited to applications that require potentials less negative than the reduction potential of the metal complexes. In order to overcome this limitation, we used Zn(2+) cations on nitrilotriacetic acid (NTA) modified carbon electrodes for the coordination of His-tagged nitrate reductase (NaR).

Enzyme-catalyzed O2 removal system for electrochemical analysis under ambient air: application in an amperometric nitrate biosensor.

Electroanalytical procedures are often subjected to oxygen interferences. However, achieving anaerobic conditions in field analytical chemistry is difficult. In this work, novel enzymatic systems were designed to maintain oxygen-free solutions in open, small volume electrochemical cells and implemented under field conditions.

Viscosity effects on eukaryotic nitrate reductase activity.

Rate-limiting processes of catalysis by eukaryotic molybdenum-containing nitrate reductase (NaR, EC 1.7.1.

Structural basis of eukaryotic nitrate reduction: crystal structures of the nitrate reductase active site.

Nitrate assimilation in autotrophs provides most of the reduced nitrogen on earth. In eukaryotes, reduction of nitrate to nitrite is catalyzed by the molybdenum-containing NAD(P)H:nitrate reductase (NR; EC 1.7.

Purification and biochemical characterization of simplified eukaryotic nitrate reductase expressed in Pichia pastoris.

NAD(P)H:nitrate reductase (NaR, EC 1.7.1.

NITRATE REDUCTASE STRUCTURE, FUNCTION AND REGULATION: Bridging the Gap between Biochemistry and Physiology.

Nitrate reductase (NR; EC 1.6.6.

Corn leaf nitrate reductase--a nontoxic alternative to cadmium for photometric nitrate determinations in water samples by air-segmented continuous-flow analysis.

Development, characterization, and operational details of an enzymatic, air-segmented continuous-flow analytical method for colorimetric determination of nitrate + nitrite in natural-water samples is described. This method is similar to U.S.