Spacer-modified, photolabile tetrasaccharides as analogues of maltopentaose are versatile probes for porcine pancreatic alpha-amylase.
The syntheses are described of methyl 4'-O-[4-S-(3-azi-4-alpha-D-glucopyranosyloxybutyl)-6-deoxy-4 -thio-alpha-D-xylo-hex-5-enopyranosyl]-alpha-maltoside (28), methyl 4-O-[4-S-(3-azi-4-alpha-maltosyloxybutyl)-6-deoxy-4-thio- alpha-D-xylo-hex-5-enopyranosyl]-alpha-D-glucopyranoside (29), and methyl 4-S-(3-azi-4-alpha-maltotriosyloxybutyl)-6-deoxy-4-thio- alpha-D-xylo-hex-5-enopyranoside (30), which are analogues of maltopentaose in which a central glucosyl unit is replaced by an acyclic, four-membered hydrocarbon spacer carrying a photolabile azi group. Only 30 was slowly cleaved by high concentrations of pancreatic alpha-amylase. The Ki values (mM) were 0.15 (28), 2.1 (29), and 2.5 (30). Deactivation of the enzyme by irradiation in the presence severely of 28-30 was 96.4%, 98.1%, and 40%, respectively. There is an indication for regiospecific photoaffinity labelling of the binding subsites of the enzyme.
Lehmann
J
J
Institut für Organische Chemie und Biochemie, Universität Freiburg, F.R.G.
Ziser
L
L
D000345:Affinity Labels / Q000138:chemical synthesis*; D000818:Animals; D001665:Binding Sites; D002240:Carbohydrate Sequence; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D010179:Pancreas / Q000201:enzymology; D010777:Photochemistry; D013552:Swine; D000516:alpha-Amylases / Q000737:chemistry*
D000345:Affinity Labels; D009844:Oligosaccharides; C019193:maltopentaose; D000516:alpha-Amylases