Method of Assay for α-Amylase Using α-Nitrophenyl β-D-Galactosyl-α-Maltooligoside as a Substrate

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We evaluated a method of assay for human α-amylase (Amy) which used? I-nitrophenyl β-Dgalactosyl-β-maltooligoside (Gal-GnPNP, n=4-7), in which D-galactose was β-(1-4)-linked (Gal-GnPNP-I, n=4-7) or β-(1-6)-linked (Gal-GnPNP-II, n=4-7) at the nonreducing end as a substrate.<BR>Gal-GnPNP-I (n=4-7) proved superior to Gal-GnPNP-II (n=4-7) under the conditions of Km and relative activity. Of the Gal-GnPNP-I (n=4-7), Gal-G5PNP-I had the best ratio of activity between pancreatic amylase (p-Amy) and salivary amylase (s-Amy), and underwent catalyzed hydrolysis at two sites by each of the human Amy isozymes, 48.8, 51.2% of p-Amy and 49.3, 50.7% of s-Amy.<BR>Our evaluation of the proposed method showed that it could obtain good results with a high degree of reproducibility; its CV was 0.31-0.71% (n=10), with non-interference except for hemolysis (3%). The coefficent of correlation between the proposed method and the previous method was high for both serum and urine (serum:β=0.999, y=0.68x+1.6, n=50; urine:β=0.999, y=0.70x+0.2, n=50).<BR>These findings suggest that Gal-G5PNP-I is suitable for application in the human α-amylase assay used in the clinical chemistry laboratory.
Japan Society of Clinical Chemistryの論文