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Appl. Environ. Microbiol., Feb 1995, 567-575, Vol 61, No. 2
A Rudiger, PL Jorgensen and G Antranikian
The gene encoding an extremely heat-stable pullulanase from the
hyperthermophilic archaeon Pyrococcus woesei was cloned and expressed in
Escherichia coli. Purification of the enzyme to homogeneity was achieved
after heat treatment of the recombinant E. coli cells, affinity
chromatography on a maltotriose-coupled Sepharose 6B column, and
anion-exchange chromatography on Mono Q. The pullulanase, which was
purified 90-fold with a final yield of 15%, is composed of a single
polypeptide chain with a molecular mass of 90 kDa. The enzyme is optimally
active at 100 degrees C and pH 6.0 and shows 40% activity at 120 degrees C.
Enzyme activation up to 370% is achieved in the presence of calcium ions
and reducing agents such as beta-mercaptoethanol and dithiothreitol,
whereas N-bromosuccinimide and alpha-cyclodextrin are inhibitory. The high
rigidity of the heat-stable enzyme is demonstrated by fluorescence
spectroscopic studies in the presence of denaturing agents such as sodium
dodecyl sulfate. At temperatures above 80 degrees C, the enzyme seems to
switch from the compact to the unfolded form, which is accompanied by an
apparent shift in the molecular mass from 45 to 90 kDa.
Copyright © 1995, American Society for Microbiology
Isolation and characterization of a heat-stable pullulanase from the hyperthermophilic archaeon Pyrococcus woesei after cloning and expression of its gene in Escherichia coli
Department of Technical Microbiology, Technical University Hamburg- Harburg, Germany.
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