Characterization of novel thermostable dextranase from Thermotoga lettingae TMO.
Biochemical properties of a putative thermostable dextranase gene from Thermotoga lettingae TMO were determined in a recombinant protein (TLDex) expressed in Escherichia coli and purified to sevenfold apparent homogeneity. The 64-kDa protein displayed maximum activity at pH 4.3, and enzyme activity was stable from pH 4.3-10. The optimal temperature was 55-60 degrees C during 15 min incubation, and the half-life of the enzyme was 1.5 h at 65 degrees C. The enzyme showed higher activity against alpha-(1 --> 6) glucan and released isomaltose and isomaltotriose as main products from dextran T2000. An unusual kinetic feature of TLDex was the negative cooperative behavior on the reaction of dextran T2000 cleavage. Enzyme activity was not significantly affected by the presence of metal ions, except for the strong inhibited by 1 mM Fe(2+) and Ag(2+). TLDex may prove useful as an enzyme for high temperature sugar milling processes.
Kim
Young-Min
YM
School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea.
Kim
Doman
D
D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D003910:Dextranase / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D003911:Dextrans; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004795:Enzyme Stability; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005936:Glucans / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000494:pharmacology; D007534:Isomaltose / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D012834:Silver / Q000494:pharmacology; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors; D014312:Trisaccharides / Q000378:metabolism
D001426:Bacterial Proteins; D003911:Dextrans; D004791:Enzyme Inhibitors; D005936:Glucans; D011994:Recombinant Proteins; D014312:Trisaccharides; C504992:alpha-1-6-glucan; C045441:isomaltotriose; D012834:Silver; D007534:Isomaltose; D007501:Iron; D003910:Dextranase