ENZYMIC-SYNTHESIS, BY TRANSGLUCOSYLATION OF A HOMOLOGOUS SERIES OF GLYCOSIDICALLY SUBSTITUTED MALTO-OLIGOSACCHARIDES, AND THEIR USE AS AMYLASE SUBSTRATES

(1 → 4)-α-d-Glucan 4-glucosyltransferase (EC2.4.1.19) of klebsiella pneumoniae transforms maltose (G2) into d-glucose (G1) and a mixture of malto-oligosaccharides (G2-G9), and maltotriose (G3) into Gl-Gll in addition to cyclo-hexa-, -hepta-, and -octa-amyloses (cG6-8). It produces a similar mixture, but with higher amounts of G2-G11, by transfer from cyclohexaamylose to G1. By using p-nitrophenyl α- and β-d-glucosides, 4 methylumbelliferyl α-d-glucoside, and strophanthyl α-d-glucoside as acceptors and cyclohexaamylose as donor, a homologous series of substituted malto-oligosaccharides having chain lengths of up to 12 d-glucose residues was produced. High-pressure liquid chromatography on Bio-Gel P2 permitted separation of these products of transferase activity on analytical and preparative scales. By the same technique, the nitration product of phenyl hepta-O-acetyl-α-maltoside, after deacetylation, was separated into about equal amounts of the o- and p-isomers. The synthetic p-nitrophenyl α-maltoside (pNPG2) was used to identify the first member of the series of biochemical transfer-products. p-Nitrophenyl maltotrioside (pNPG3) and maltotetraoside (pNPG4) were shown to be the higher homologues. They are very good substrates for human and pig-pancreatic alpha amylase. This substrate behavior may be measured conveniently in the case ofpNPG3 by the rapid liberation of nitrophenolate; the enzyme used pNPG4 only on addition of α-d-glucosidase. Human-parotis amylase of equal starch-splitting activity as the pancreatic enzyme acts upon pNPG3 and pNPG4 but about 100 times more slowly. © 1978.