Makise J, Saito E, Obuchi M, Kanayama M, Harakawa K, Yoshida K
Central Clinical Laboratory, Yokosuka Kyosai Hospital, Kanagawa, Japan.
Clin Chem. 1990 Feb;36(2):319-22.
We have improved the kinetic rate assay method for determining N-acetyl-beta-D-glucosaminidase (EC 3.2.1.30; NAG) activity in urine with use of the synthetic substrate, 2-chloro-4-nitrophenyl-N-acetyl-beta-D-glucosaminide (CNP-NAG), reported previously (Clin Chem 1988;34:2140-2). To increase the solubility of this substrate, we used crown ether (15-crown-5-ether) and ethylene glycol. In addition, we used for the standard solution NAG from human placenta, with specificity corresponding to that of human urine, so that values obtained with the CNP-NAG method and a p-nitrophenyl-NAG method ("MEI Assay NAG") correlated almost completely (r = 0.995, n = 29). Reference values for urinary NAG activity determined by the CNP-NAG method were established for untimed urine specimens from 674 healthy volunteers. The normal reference interval (mean +/- 2 SD) for NAG: 1.6-15.0 (mean 4.9) U per gram of creatinine.
我们改进了动力学速率测定方法，该方法使用先前报道的合成底物2-氯-4-硝基苯基-N-乙酰-β-D-氨基葡萄糖苷（CNP-NAG）来测定尿液中N-乙酰-β-D-氨基葡萄糖苷酶（EC 3.2.1.30；NAG）的活性（《临床化学》1988年；34：2140 - 2）。为提高该底物的溶解度，我们使用了冠醚（15-冠-5-醚）和乙二醇。此外，我们将人胎盘来源的NAG用作标准溶液，其特异性与人尿的特异性相当，因此用CNP-NAG方法和对硝基苯基-NAG方法（“MEI Assay NAG”）获得的值几乎完全相关（r = 0.995，n = 29）。通过CNP-NAG方法测定了674名健康志愿者随机尿标本中尿NAG活性的参考值。NAG的正常参考区间（均值±2标准差）为每克肌酐1.6 - 15.0（均值4.9）U。
