Action patterns of amylolytic enzymes as determined by the [1-14C]malto-oligosaccharide mapping method.
A valuable technique for oligosaccharide mapping, utilizing radioactive malto-oligosaccharides, multiple-ascent p.c., and radioautography, has been developed for identifying the action patterns of the glucoamylase isozymes, alpha-amylases, beta-amylase, glucosyltransferase, and glucanosyltransferase. The glucoamylase isozymes act by multi-chain mechanisms on malto-oligosaccharides and most likely on starch and glycogen. The alpha-amylases act endo-wise and randomly hydrolyze alpha-(1----4)- but not alpha-(1----6)-glucosidic bonds. These amylases may act by single-chain and/or multi-chain mechanisms, depending on the number of hydrolytic attacks per single encounter of the enzyme and the substrate. The beta-amylases hydrolyze malto-oligosaccharides by a multi-chain mechanism. A fungal glucosyltransferase from Aspergillus niger transfers glucose units by a single-chain mechanism from maltose to glucosyl acceptors to yield new gluco-oligosaccharides with alpha-(1----4) and alpha-(1----6) linkages. A novel type of transferase isolated from Bacillus subtilis acts by a multi-chain mechanism and transfers segments of 2 to 5 glucose residues from malto-oligosaccharides to acceptor co-substrates. An alpha-amylase from the same organism removes maltotriose units from the non-reducing ends of oligosaccharides by a multi-chain mechanism.
Pazur
J H
JH
Paul M. Althouse Laboratory, Pennsylvania State University, University Park 16802.
Marchetti
N T
NT
D000681:Amylases / Q000378:metabolism*; D001345:Autoradiography; D005964:Glucosyltransferases / Q000378:metabolism; D009844:Oligosaccharides; D000516:alpha-Amylases / Q000378:metabolism; D001614:beta-Amylase / Q000378:metabolism
D009844:Oligosaccharides; D005964:Glucosyltransferases; D000681:Amylases; D000516:alpha-Amylases; D001614:beta-Amylase