細菌のα‐グルコシダーゼ

Abstract

α-Glucosidases have been found in a number of strains from different bacterial species. Among these enzymes, however, only five have been purified homogeneously from the following bacteria, Pseudomonas SB 15 (A. Amemura et al ., 1974), Bacillus cereus (Y. Yamasaki and Y. Suzuki, 1974), Bacillus thermoglucosidius (Y. Suzuki et al ., 1979), B, cereus (Y. Suzuki et al., 1982), Bacillus coagulans (Y. Suzuki et al., 1983), Bacillus stearothermophilus (Y . Suzuki and M. Shinji, 1983), and Bifidobacterium adolescentis (I. Igaue et al ., 1983). Also, highly purified enzyme samples have been obtained from Streptococcus mitis (G . J. Walker and A. Pulkownik, 1973), Pseudomonas fluorescens (A. A. Guffanti and W. A. Corpe, 1976), Bacillus subtilis (L.-H. Wang and P. A. Hartman, 1976), Bacillus amyloliquefaciens (H. Urlaub and G . Wober, 1978), thermophilic Bacillus sp. (Y. Suzuki et al., 1978), Bacillus brevis (S. J. McWethy and P. A. Hartman, 1979), and Flavobacterium sp. (H. Bender, 1981). These enzymes can be classifiedinto 4 groups in terms of their substrate specificities: 1) exo-oligo-1, 6-glucosidases from S. mitis, B. cereus, B. coagulans, and B. the rmoglucosidius, 2) exo-α-1, 4-glucosidase from B . stearothermophilus, 3) α-glucosidases active for various oligo- and polysaccharides from Pseudomonas SB 15, B. adolescentis, B, amyloliquefaciens, and Flavobacterium sp ., and 4) a-glucosidases highly specific for maltose from B. cereus, B. subtilis, B, brevis, thermophilic Bacillus sp., and lavobacterium fuorescens. B. stearothermophilus exo-α-1, 4-glucosidase is a hitherto unrecognized type of α-glucosidase, since the enzyme activity is exclusively narrowed to successive splitting of α-1, 4-bonds with the release of α-glucose residues from the non-reducing termini of lowmolecular weight maltosaccharides, α-limit dextrins, dextrin, amylose, amylopectin, soluble starch, and glycogen among a number of naturally distributed sugars tested, and since the α-1, 6-bonds in these saccharides are not hydrolyzed by the enzyme at all.