title: Structure of the gene encoding cyclomaltodextrinase from Clostridium thermohydrosulfuricum 39E and characterization of the enzyme purified from Escherichia coli.
abstract: Clostridium thermohydrosulfuricum 39E, a gram-positive thermophilic anaerobic bacterium, produced a cyclodextrin (CD)-degrading enzyme, cyclodextrinase (CDase) (EC 3.2.1.54). The enzyme was purified to homogeneity from Escherichia coli cells carrying a recombinant multicopy plasmid that contained the gene encoding for thermophilic CDase. The purified enzyme was a monomer with an M(r) of 66,000 +/- 2,000. It showed the highest activity at pH 5.9 and 65 degrees C. The enzyme hydrolyzed alpha-, beta-, and gamma-CD and linear maltooligosaccharides to yield maltose and glucose. The Km values for alpha-, beta-, and gamma-CD were 2.5, 2.1, and 1.3 mM, respectively. The rates of hydrolysis for polysaccharides (starch, amylose, amylopectin, and pullulan) were less than 5% of the rate of hydrolysis for alpha-CD. The entire nucleotide sequence of the CDase gene was determined. The deduced amino acid sequence of CDase, consisting of 574 amino acids, showed some similarities with those of various amylolytic enzymes.
authors.affiliation: Department of Biochemistry, Michigan State University, East Lansing 48824.
authors.forename: S M
authors.initials: SM
authors.lastname: Podkovyrov
authors.forename: J G
authors.initials: JG
authors.lastname: Zeikus
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002853:Chromatography, Liquid; D002855:Chromatography, Thin Layer; D003013:Clostridium / Q000201:enzymology* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics*; D005798:Genes, Bacterial; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid; D013696:Temperature
chemical_list: D006026:Glycoside Hydrolases; C048745:cyclomaltodextrinase