Reaction mechanism of a new glycosyltrehalose-producing enzyme isolated from the hyperthermophilic archaeum, Sulfolobus solfataricus KM1

An amylolytic activity, which converts soluble starch to alpha,alpha-trehalose (trehalose), was found in the cell homogenate of the hyperthermophilic, acidophilic archaeum Sulfolobus solfataricus KM1. Two enzymes, a glycosyltransferase and an amylase, which are essential for this activity, were purified to homogeneity. A glycosyltransferase catalyzed the conversion of maltooligosaccharides to glycosyltrehaloses. Based on a detailed analysis of the reaction products, kinetic parameters, and an experiment using H-3-labeled substrates, it was verified that glycosyltransferase transferred an oligomer segment of maltooligosaccharide to the C1-OH position of glucose, located at the reducing end of the maltooligosaccharide, to produce a glycosyltrehalose having an alpha-1,1 linkage, The reaction appears to be intramolecular, Nine strains of the Sulfolobaceae family were found to have glycosyltransferases.