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Applied and Environmental Microbiology, March 2006, p. 2206-2211, Vol. 72, No. 3
0099-2240/06/$08.00+0     doi:10.1128/AEM.72.3.2206-2211.2006
Copyright © 2006, American Society for Microbiology. All Rights Reserved.

Identification and Characterization of a Novel Intracellular Alkaline -Amylase from the Hyperthermophilic Bacterium Thermotoga maritima MSB8

Institute of Microbiology and Genetics, University of Goettingen, Grisebachstrasse 8, D-37077 Goettingen, Germany

Received 8 September 2005/ Accepted 10 January 2006

The gene for a novel -amylase, designated AmyC, from the hyperthermophilic bacterium Thermotoga maritima was cloned and heterologously overexpressed in Escherichia coli. The putative intracellular enzyme had no amino acid sequence similarity to glycoside hydrolase family (GHF) 13 -amylases, yet the range of substrate hydrolysis and the product profile clearly define the protein as an -amylase. Based on sequence similarity AmyC belongs to a subgroup within GHF 57. On the basis of amino acid sequence similarity, Glu185 and Asp349 could be identified as the catalytic residues of AmyC. Using a 60-min assay, the maximum hydrolytic activity of the purified enzyme, which was dithiothreitol dependent, was found to be at 90°C. AmyC displayed a remarkably high pH optimum of pH 8.5 and an unusual sensitivity towards both ATP and EDTA.