Printed in U. S. A. Purification, Characterization, and Nucleotide Sequence of the Thermolabile a-Amylase from the Antarctic Psychrotroph

• Main Authors: Georges Feller, Thierry Lonhienne, Christophe Deroanne, Cecille Libioulle, Jozef Van Beeumenq, Charles Gerday
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1029.3981; http://orbi.ulg.ac.be/bitstream/2268/16397/1/JBC_1992_AHAwt.pdf

The a-amylase excreted by the antarctic bacterium Alteromonas haloplanctis was purified and the corre-sponding amy gene was cloned and sequenced. N- and C-terminal amino acid sequencing were used to estab-lish the primary structure of the mature A. haloplanctis a-amylase which is composed of 453 amino acids with a predicted M, of 49,340 and a PI of 5.5. Three Ca2’ ions are bound per molecule and its activity is modu-lated by chloride ions. Within the four consensus se-quences, Asp-174, Glu-200, and Asp-264 are the pro-posed catalytic residues. The psychrotrophic A. halo-planctis a-amylase is characterized by a high amylolytic activity at low temperatures, a reduced ap-parent optimal temperature, and typical thermody-namic activation parameters. A. haloplanctis a-amy-