Figure 2
HSQC spectra of pullulan degradation by purified Alicyclobacillus α-amylase recorded with extensive sampling of the 13C dimension. Only the α-anomeric spectral region is shown. Three different glucopyranosyl units occur in pullulan (left). Signals of α-1,6 anomeric glucopyranosyl units at the nonreducing end emerge (see the inset in the middle spectrum) owing to cleavage at the indicated position (middle top). Pullulan is degraded to panose as the final product (right), as demonstrated by comparison with an authentic standard (grey). These experiments identify the pullulan-cleaving activity of Alicyclobacillus α-amylase as that of a panose-forming neopullulanase (EC 3.2.1.135). |