The mechanism of action of alpha-amylase from Lactobacillus fermentum on maltooligosaccharides

The action pattern of Lactobacillus fermentum alpha-amylase (FERMENTA) was examined using a series of maltooligosaccharides (G2-G7) as substrates. Structurally, this enzyme has a molecular mass (106 kDa) almost twofold higher than alpha-amylases from mammalians and cereals. The product pattern was investigated through an analysis of products and substrates using HPAEC with pulsed amperometric detection. FERMENTA was consistent with an endo-type of amylase. The bond cleavage frequencies were studied using maltooligosaccharides of various chain lengths as substrate, i.e. maltose up to maltoheptaose and DP 4900-amylose catalyzed by FERMENTA. The catalytic efficiency (k(cat)/K-m) increased with chain length from maltose (8.7 x 10(4)M (-1)s(-1)) up to amylose (1 x 10(9) M(-1)s(-1)). These action pattern results revealed that FERMENTA can readily cleave the third linkage from the reducing end of the maltooligosaccharides (G5-G7). (c) 2006 Elsevier B.V. All rights reserved