Assay for Simultaneous Determination of β-Cyclodextrin Glycosyltransferase (β-CGTase) and Amylase

A new procedure was developed for the simultaneous determination of β-cyclodextrin glycosyltransferase (β-CGTase) and amylase activities in Bacillus macerans cultures. The new amylase assay branched off from the β-CGTase activity measurement according to Kaneko et al. (J. Jpn. Soc. Starch Sci. 34 [1987], 45–48), included water-soluble starch as substrate and based on the well-characterized K3[Fe(CN)6] reducing sugar analysis procedure. The assay had excellent within-run and between-run CVs, and also had an excellent correlation with the widely used 3,5-dinitrosalicylic acid method of Bernfeld (Meth. Enzymol. 1 [1955], 149–158) using Bacillus licheniformis a-amylase as a model enzyme at 50°C. Neither high cyclodextrin glycosyltransferase activities nor the self-degradation of starch interfered with the new amylase assay.