N-acetyl-β-D-glucosidase (NAG) is widely distributed in various tissues. It is an intracellular lysosomal
enzyme. The activity of Nag can be used for the early diagnosis of tubulointerstitial nephritis, urinary tract
infection, diabetic nephropathy syndrome, hypertensive nephropathy, rejection after kidney transplantation
and nephrotic syndrome.
Nag decomposes n - β - acetylglucosamine to produce p - nitrophenol. It has a maximum absorption peak
at 400 nm. NAG activity was calculated by measuring the change of absorbance at 400 nm.
Required but Not Provided:
Spectrophotometer, balance, centrifuge, water-bath, transferpettor, 1 mL glass cuvette, EP tube, mortar/
homogenizer and distilled water.
Protocol
I. Preparation:
1. Tissue: according to the ratio of mass (g): extraction volume (mL): 1:5-10 to add the extract solution. It
is suggested that add 1 mL of extract solution to 0.1 g of tissue. Homogenize on ice. Centrifuge at 15000 g
4℃ for 10 min. Take the supernatant on ice for test.
2. Bacteria or cell: according to the ratio of 104 cells: extract solution volume (mL) 500-1000:1. It is
suggested to take about 500 million bacteria/cell and add 1 mL extraction solution. Bacteria/cell is split by
ultrasonication (power 300w, ultrasonic 3s, interval 7s, total time 3 min). Centrifuge at 15000 g 4℃ for 10
min. Take the supernatant on ice for test.
3. Serum (plasma) and other liquid: detect directly.
II. Determination
