| Autor: |
Bautista, Vanesa, Esclapez, Julia, Pérez-Pomares, Francisco, Martínez-Espinosa, Rosa, Camacho, Mónica, Bonete, María |
| Předmět: |
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| Zdroj: |
Extremophiles; Jan2012, Vol. 16 Issue 1, p147-159, 13p |
| Abstrakt: |
A cyclodextrin glycosyltransferase (CGTase, EC 2.4.1.19) was successfully isolated and characterized from the halophilic archaeon Haloferax mediterranei. The enzyme is a monomer with a molecular mass of 77 kDa and optimum activity at 55°C, pH 7.5 and 1.5 M NaCl. The enzyme displayed many activities related to the degradation and transformation of starch. Cyclization was found to be the predominant activity, yielding a mixture of cyclodextrins, mainly α-CD, followed by hydrolysis and to a lesser extent coupling and disproportionation activities. Gene encoding H. mediterranei CGTase was cloned and heterologously overexpressed. Sequence analysis revealed an open reading frame of 2142 bp that encodes a protein of 713 amino acids. The amino acid sequence displayed high homology with those belonging to the α-amylase family. The CGTase is secreted to the extracellular medium by the Tat pathway. Upstream of the CGTase gene, four maltose ABC transporter genes have been sequenced ( malE, malF, malG, malK). The expression of the CGTase gene yielded a fully active CGTase with similar kinetic behavior to the wild-type enzyme. The H. mediterranei CGTase is the first halophilic archaeal CGTase characterized, sequenced and expressed. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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