Urease is a highly efficient catalyst for the hydrolysis of urea with a rate approximately 10 14 times the rate of the noncatalyzed reaction. It has a long and distinguished history in the development of enzymology. In this work the properties of urease and its applications in biotechnology are reviewed, including urea content analysis in blood, urine, alcoholic beverages, natural water and environmental wastewaters; analysis of heavy metal content in natural waters, wastewaters and soil; determination of creatinine, arginine and IgG; urea removal from artificial kidney dialyzates, alcohol beverages and fertilizer wastewaters; wastewater reclamation for life support systems in space; pH control or shift for multi-enzyme reaction system; and urea hydrolysis as sources of ammonia or carbon dioxide in special cases. Future research trends are also outlined.

Review Properties and Applications of Urease

The Free Amino Nitrogen (FAN) content of wort prescribes efficient yeast cell growth and fermentation performance. FAN consists of the individual amino acids, small peptides and ammonia ions formed during malting, the relative amounts of which vary. In this paper, the individual constituents of FAN were dissected and their effect on both ale and lager fermentations determined. The patterns of amino acid and small peptide uptake and the changes in extracellular protease activity revealed the dynamic environment that develops during fermentation. Lysine and methionine, previously identified as key amino acids in wort fermentation, were investigated further.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/j.2050-0416.2007.tb00249.x

Elucidation of the Role of Nitrogenous Wort Components in Yeast Fermentation

In the past decade, reaction detection has rapidly gained importance as a means to improve the sensitivity and selectivity of detection in HPLC. Today, most attention is being paid to post-column reaction detection with final analysis via fluorescence monitoring. Novel developments involve the use of solid-phase reactors for reagent addition or catalysis (ion-exchange resins, immobilized enzymes), and the increasing use of systems based on peroxyoxalate chemiluminescence detection. The rapidly growing number of reported applications indicates that commercialization of reaction-detection equipment is urgently needed.

A review of reaction detection in HPLC

Exceptionally high stability of urease covalently immobilized on silica, tungsten, and poly(tetrafluoroethylene) (Teflon) supports has been observed by using a novel immobilization protocol which links the enzyme via its surface-exposed carboxylic groups (rather than conventionally used amino groups) to phospholipid-coated surfaces. Silanization of each of the three solid supports with [N-[11-(trifluoroacetamido)undecanoyl]amino]propyltriethoxysilane, followed by removal of the trifluoroacetyl protective group, furnished the required amino-functionalized surfaces

Enhanced stability of urease immobilized onto phospholipid covalently bound to silica, tungsten, and fluoropolymer surfaces

Currently, the best and most reliable HPLC (high-performance liquid chromatography) detectors are UV-VIS absorbance, fluorescence, and electrochemical detectors. It is attractive to try to expand their range of application by using suitable chemical derivatization techniques to convert the analytes of interest with their originally poor detection properties into compounds that can be detected with high sensitivity with these detectors. Besides an improvement of the detection properties, the chemical reaction can also enhance the selectivity of the total analytical method. The derivatization can be carried out either prior to the HPLC separation or by doing the reaction in an on-line postcolumn mode. Comparative advantages and disadvantages of these two approaches have been discussed previously. This paper will discuss on-line postcolumn derivatization. A general scheme of an HPLC system equipped with an on-line postcolumn reaction detector is given. 40 references, 6 figures, 2 tables.

R.P.J. Snellings

Papers

Determination of urea and ammonia using ion-pair liquid chromatography with on-line post-column derivatization in an enzymatic solid-phase reactor