Syntheses of subtractively modified 2-chloro-4-nitrophenyl beta-maltopentaosides and their application to the differential assay of human alpha-amylases.

Three novel maltopentaosides, 2-chloro-4-nitrophenyl O-(6-deoxy-alpha-D-xylo-hex-5-enopyranosyl)-(1-->4)-tris[O-alpha-D - glucopyranosyl-(1-->4)]-beta-D-glucopyranoside (3), 2-chloro-4-nitrophenyl O-(6-deoxy-alpha-D-glucopyranosyl)-(1-->4)-tris[O- alpha-D-glucopyranosyl-(1-->4)]-beta-D-glucopyranoside (10), and 2-chloro-4-nitrophenyl O-(3,6-anhydro-alpha-D-glucopyranosyl)-(1-->4)-tris[O-alpha-D-glucopyran osyl- (1-->4)]-beta-D-glucopyranoside (26) were synthesized by chemical and enzymatic reactions. Two human alpha-amylases, salivary alpha-amylase (HSA) and pancreatic alpha-amylase (HPA), hydrolyzed 3 and 10 with the same specificity, almost entirely at a single D-glucosidic linkage, but had no hydrolytic activity for 26. Compound 3 was hydrolyzed by each of these amylases at an approximately equal rate, while 10 was hydrolyzed by HSA 4-fold faster than by HPA. Taking advantage of the difference in the hydrolytic rate of 10, we developed a new method for the differential assay of these two human alpha-amylases.