等電点電気泳動MCP-NAG法による尿中N-acetyl-β-D-glucosaminidase アイソザイムの測定

抄録

A lysosomal enzyme, N-acetyl-β-D-glucosaminidase (NAG) is abundant in kidneys and has various isoenzymes. An increase in urinary NAG activity is found in workers exposed to nephrotoxic chemicals. Urinary isoenzyme determination is accepted as a method of identifying affected nephron lesions. We did a NAG isoenzymes determination using isoelectric focusing and the MCP-NAG method. This method was applicable to normal urine with condensation by Centricut (2500G×60min). In 17 normal urine samples, 77.5% of the total NAG was found as a NAG A form, and 22.5% as a NAG B form. These values agreed well with earlier reports. The calibration curve of NAG activity in electrofocused gels gave a good linearity over the range of 0-206U/L. The reproducibility was sufficient since the intra-assay coefficient of variation was 5.6% (n=10). The separation level of isoelectric focusing is regarded to be better than that of the electrofocusing procedure. Moreover, 15 samples can be analyzed at once. Thus, our method satisfied the requirements for separation ability, linearity, reproducibility, and time-saving. This method will be applied to workers exposed to nephrotoxic chemicals in the future.