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

The action pattern of Lactobacillus fermentum α-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 α-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 (kcat/Km) increased with chain length from maltose (8.7 × 104 M−1 s−1) up to amylose (1 × 109 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).