Studies on Mechanism of Substrate Confirmation, Modification of Function, and Utilization for Carbohydrate-Hydrolase and Synthase

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(1) A cyclodextrin glucanotransferase from alkaliphilic Bacillus sp. was crystallized, and its three dimensional structure was analyzed by x-ray (1.8*) . The enzyme was modified by exchanging the four amino acid residues directly involved in catalytic activity.(2) Primary structure of B.stearothermophilus alpha-glucosidase was deduced from cloned cDNA.(3) Soybean beta-amylase and a substrate analog complex was analyzed by x-ray crystallography. The mechanism in the substrate confirmation was revealed by the x-ray analysis.(4) Catalytic ionizable groups of Arthrobacter grobiformis isomalto-dextranase were kinetically identified. The complete primary structure of the enzyme was deduced from the analysis of cDNA.(5) Heterogeneous cyclodextrins (CD) were synthesized through transfer reaction of alpha-galactosyl or alpha-mannosyl residue to branched CD by alpha-galactosidase and alpha-mannosidase.(6) Subsite structure of cycloamylose glucanotransferase was evaluated by the subsite theory, and the production method of isopanose from maltose was established by the enzyme.(7) From the cell suspension culture of sweet potato tuber, a monomeric beta-amylase having the same level activity as tetrameric enzyme was successfully obtained in a high yield.(8) Reaction specificity of Aspergillus oryzae alpha-amylase was elucidated by a chemical modiification with omicron-phthalaldehyde.(9) Amino acid sequence in active site and a catalytic amino acid residue of sugar beet alpha-glucosidase were identified by chemical modification.(10) Action mechanism of novel glycosylation (condecsation, transfer reaction and hydrolysis) was elucidated for Trichoderma viride cellulase II-b.(11) A novel alpha-amylase was purified from Xanthomonas campestris, and the properties were examined.(12) Substrate specificties of two novel alpha-amylases (TVA I and II) cloned in E.coli were clarified and compared with each other.