Enzymatic method for the determination of L-arginine, urea and ammonia (Yeast Available Nitrogen -YAN). Based on the spectrophotometric measurement of NADPH consumed through the reactions, after addition of arginase (ARG), urease (URE) andglutamate dehydrogenase (GlDH).
The determination of YAN (L-arginine, urea and ammonia) is an indicator of the amount of nitrogen available for yeast growth. YAN comprises three components: free ammonium ions, amino nitrogen from free amino acids and from the side chain of L-arginine. As the concentrations of these compounds vary widely, each compound must be determined for the accurate calculation of YAN, which is possible by using this kit. In wine industry, the YAN can be managed by addition of nutrient supplements to grape juice prior to/during fermentation.
This rapid and simple stereo-specific enzymatic method is used for the simultaneous determination of L-arginine, urea and ammonia (yeast available nitrogen, YAN) in foodstuffs and in the wine industry (grape juice, fermenting must and fermenting wine). This kit is suitable for both manual and micro-volume formats.
Solution 1. TEA buffer (25 mL, 0.5 M, pH 8.0). Stable for 2 years at 4 °C. Tablets 2. 125 tablets of NADPH supplied in a plastic vial containing desiccant. Allow this container to warm to room temperature (in the presence of a desiccant if possible) before opening to remove tablets. Stable for 3 years when stored dry at 4 °C or -20 °C. Add 5 tablets per mL of solution 1 (Solution 1+2) to a test tube and stir intermittently over 2-3 min. Use 0.5 mL of Solution 1+2 per assay, including blank reaction. Suspension 3. Glutamate dehydrogenase (GlDH) is provided in 2.5 M lithium sulphate (EC 22.214.171.124; 1.1 mL, 475 U/mL). Stable for 2 years at 4 °C. Swirl bottle before use. Suspension 4. Urease is provided in 2.5 M lithium sulphate (EC 126.96.36.199; 1.1 mL, 3000 U/mL). Stable for 2 years at 4 °C. Swirl bottle before use. Suspension 5. L-Arginase is provided in 2.5 M lithium sulphate (EC 188.8.131.52; 1.1 mL, 8300 U/mL). Stable for 2 years at 4 °C. Swirl bottle before use. Solution 6. Ammonia standard solution (5 mL, 0.04 mg/mL) in 0.02 % (w/v) sodium azide. Stable for 2 years at 4 °C. This standard should be used when there is doubt about the method accuracy.Powder 7. L-Arginine standard powder (~2 g). Stable for 2 years when stored dry at 4 °C. Accurately weigh approx. 100mg of L-arginine into a 1 L volumetric flask, fill to the mark with distilled water and mix thoroughly. This control solution is stable for ~3 months at -20 °C.
Compatible Sample Types:
Grape juice, wine and wine must, biological cultures and biological samples.
Features & Benefits:
Nitrogen determination without formaldehydeRapid reactionsStable enzyme suspensions
Reaction volume: 2.66 mLRange: L-Arginine – 50-400 mg/L; Urea – 20-140 mg /L; Ammonia – 10-70 mg /LDetection limit: L-Arginine – 0.37 mg/L ; Urea – 0.13 mg/L; Ammonia – 0.07 mg/L