β-N-acetylglucosaminidase

β-N-acetylglucosaminidase (NAG) hydrolyzes β-N-acetylglucosaminide and also hydrolyzes β-N-acetylgalactosamine. The enzyme is widely present in various tissues, organs, body fluids, and blood cells, and is an acidic hydrolase in lysosomes. The measurement methods are colorimetry and fluorometry. Basic Information Specialist classification: urinary examination classification: biochemical examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Rare. Normal value: Serum β-N-acetylglucosaminidase: 15.14-27.94 U/L Above normal: Renal tubular disease heavy metals (mercury, lead, cadmium, etc.) and drug-induced renal damage, ischemia, hypoxia, blood loss, shock, etc. can cause an increase in NAG activity. negative: Positive: Tips: According to the nutritional status of the whole body, milk, eggs, fruits, soy milk, etc. are given in the meal. Normal value 1, p-nitrophenol colorimetric method: serum NAG21.54 ± 6.4U / L, urine NAG is normally distributed, the median is 9.13U / g creatinine, the 95th percentile upper limit is 16.10U / g Creatinine. 2. Fluorescence method: Adult serum: 9.94 ± 2.O7U / L. Adult urine: 6.39 ± 3.19 U / LCre. Clinical significance The determination of blood and urine NAG activity is sensitive to the changes of renal parenchymal lesions, especially acute injury and active disease, and is mainly used for early renal injury monitoring and disease observation. 1, renal tubular disease heavy metals (mercury, lead, cadmium, etc.) and drug-induced kidney damage, ischemia, hypoxia, blood loss, shock, etc. can cause an increase in NAG activity. 2, nephrotic syndrome urinary NAG often increased significantly, the remission period decreased, rapid recovery when recurrence, it can be used as an indication for clinical observation. The acute phase of glomerulonephritis varies greatly, but the change is smaller than that of renal tubular injury. 3, the location of urinary tract infection diagnosis of acute and chronic pyelonephritis urinary NAG rise, can be distinguished from simple cystitis. Can be used for the diagnosis of early upper urinary tract infections. 4, renal transplant rejection monitoring renal transplant rejection early NAG can be increased, more sensitive than urine protein, serum creatinine, creatinine clearance. 5, early diagnosis of diabetic nephropathy, diabetic nephropathy, elevated urine NAG, early diagnosis of this disease is better than urinary albumin and β2-microglobulin. High results may be diseases: nephrotic syndrome, urinary tract infections (1) p-nitrophenol colorimetric method: 1 The substrate p-nitrophenol should be purified and pre-formed at 50 ° C for 24 h. The concentration was adjusted to 0.04 mmol/L with 10 mmol/L NaOH, and the absorption curve was scanned with a narrow bandwidth spectrophotometer, λmax = 401 nm, according to the IFCC standard, Aλmax = 0.7316 to 0.7388, and Eλmax = 18380 ± 90 (25 ° C). 2 The solubility of the substrate is small. When preparing, it should be adjusted to a paste with an appropriate amount of pH 4.6 buffer, and then gradually add the buffer to the required amount. 3 When the measurement results are in the ultra-linear range, the specimen should be diluted with physiological saline and retested. The result is multiplied by the dilution factor. 4 Urine enzyme concentration is greatly affected by urine volume, 24h urine volume should be retained. If the enzyme excretion rate is calculated by the ratio of NAG/g creatinine, that is, it is not affected by concentration or dilution of urine, and no need to leave 24 hours of urine. (2) Fluorescence method: 1 Fluorescence method for measuring NAG has a domestic kit, which has high sensitivity and is not affected by urine. 2 It can also be used with Shanghai No.3 Analytical Instrument Factory to produce 930 fluorescence photometer, excitation filter 360, and emission filter (400+450) composite, with satisfactory results. 3 The concentration of each component in the enzyme reaction solution is: 1.33 mmol/L of substrate, 20 mmol/L of citric acid, and 432 mmol/L of Na2HPO. 4 Solvents used in the reagents should be distilled water, the substrate should be free of 4-MU, BSA should be free of the enzyme or heated at 50 °C for 2h. 5 NAG in serum is stable for several hours to several days at 4 ° C, and stable for several months at -20 ° C. The urine specimen was stable at 4 ° C for 1 week, and citrate anticoagulated plasma was also used. 6β-N-acetylglucosaminide can be catalyzed by two enzymes, one is β-N-acetylglucosaminidase (EC 3.2.1.30), and the other is β-N-acetylglucosidase (EC3) .2.1.52) Only EC3.2.1.30 or EC3.2.1.52 can be defined for purified enzymes. The NAG, which is often referred to in the domestic literature, is strictly named after the substrate used, rather than the specificity of the enzyme for the substrate. Therefore, the current foreign literature is often referred to as β-N-acetylglucosaminidase. Inspection process (1) p-nitrophenol colorimetric mixing, at 405 nm wavelength, 1 cm optical path, distilled water zero, read the absorbance of each tube, and check the standard curve with the difference of (AU-AC). 1 The substrate p-nitrophenol should be purified and pre-formed at 50 ° C for 24 h. The concentration was adjusted to 0.04 mmol/L with 10 mmol/L NaOH, and the absorption curve was scanned with a narrow bandwidth spectrophotometer, λmax = 401 nm, according to the IFCC standard, Aλmax = 0.7316 to 0.7388, and Eλmax = 18380 ± 90 (25 ° C). Molar absorption coefficient according to p-nitrophenol 2 The solubility of the substrate is small. When preparing, it should be adjusted to a paste with an appropriate amount of pH 4.6 buffer, and then gradually add the buffer to the required amount. 3 When the measurement results are in the ultra-linear range, the specimen should be diluted with physiological saline and retested. The result is multiplied by the dilution factor. 4 Urine enzyme concentration is greatly affected by urine volume, 24h urine volume should be retained. If the enzyme excretion rate is calculated by the ratio of NAG/g creatinine, that is, it is not affected by concentration or dilution of urine, and no need to leave 24 hours of urine. (2) Fluorescence spectrophotometry: firstly dilute serum or urine with a buffer containing no bovine serum albumin (BSA), Mix, the excitation wavelength is 364 nm, the emission wavelength is 448 nm, to stop the liquid zero adjustment, and the fluorescence intensity of the 6 μmol/L 4-MU tube is adjusted to 100, and the fluorescence intensity of the blank tube and the measuring tube are respectively measured. 1 Fluorescence method for measuring NAG has a domestic kit, which has high sensitivity and is not affected by urine. 2 It can also be used with Shanghai No.3 Analytical Instrument Factory to produce 930 fluorescence photometer, excitation filter 360, and emission filter (400+450) composite, with satisfactory results. 3 The concentration of each component in the enzyme reaction solution is: 1.33 mmol/L of substrate, 20 mmol/L of citric acid, and 432 mmol/L of Na2HPO. 4 Solvents used in the reagents should be distilled water, the substrate should be free of 4-MU, BSA should be free of the enzyme or heated at 50 °C for 2h. 5 NAG in serum is stable for several hours to several days at 4 ° C, and stable for several months at -20 ° C. The urine specimen was stable at 4 ° C for 1 week, and citrate anticoagulated plasma was also used. 6β-N-acetylglucosaminide can be catalyzed by two enzymes, one is β-N-acetylglucosaminidase (EC 3.2.1.30), and the other is β-N-acetylglucosidase (EC3) .2.1.52) Only EC3.2.1.30 or EC3.2.1.52 can be defined for purified enzymes. The NAG, which is often referred to in the domestic literature, is strictly named after the substrate used, rather than the specificity of the enzyme for the substrate. Therefore, the current foreign literature is often referred to as β-N-acetylglucosaminidase.

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