Stabilities of N -acetyl-β- d -glucosaminidase (NAG) isoenzymes in urine: advantage of NAG isoenzyme B measurement in clinical applications
| Autor: | Yoko Kosugi, Akira Noto, Nozomu Takeuchi, Kiyohisa Uchida, Yoshito Numata, Atsushi Morita |
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| Rok vydání: | 1998 |
| Předmět: |
Hot Temperature
Urinary system Clinical Biochemistry Urine urologic and male genital diseases Biochemistry Isozyme In vivo Acetylglucosaminidase Enzyme Stability Humans Glucosaminidase Incubation chemistry.chemical_classification Pyelonephritis biology urogenital system Biochemistry (medical) Bacterial Infections General Medicine Hydrogen-Ion Concentration Enzyme assay Isoenzymes Enzyme chemistry biology.protein |
| Zdroj: | Clinica Chimica Acta. 278:35-43 |
| ISSN: | 0009-8981 |
| DOI: | 10.1016/s0009-8981(98)00157-0 |
| Popis: | N -Acetyl-β- d -glucosaminidase (NAG) is a widely used urinary enzyme for the assessment of renal diseases. We studied the stabilities of NAG isoenzymes in urine at 37°C by enzyme assay and ELISA using a model simulating in vivo conditions. The stabilities were found to be affected by the pH. Under mild acidic condition (about pH 6), there was no significant loss of enzymatic activity of NAG isoenzyme A, enzymatic activity of NAG isoenzyme B and immunological activity of NAG isoenzyme B even after 8 h incubation. In contrast, under alkaline condition (about pH 8), the enzymatic activity of NAG isoenzyme A was rapidly lost, whereas both enzymatic and immunological activities of NAG isoenzyme B were maintained at more than 80% of their initial values. Also, we found that the ratios of endogenous NAG isoenzyme B to total NAG were elevated in alkaline urine samples. These results indicate that NAG isoenzyme A, which is a major isoenzyme in normal urine (pH 5–7), seems to be inactivated in alkaline urine. Our results suggest that for alkaline urine, NAG isoenzyme B should be measured to avoid misinterpretation of total NAG enzymatic activities. |
| Databáze: | OpenAIRE |
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