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Purification and characterization of a novel thermostable 4-alpha-glucanotransferase of Thermotoga maritima cloned in Escherichia coli.
- Source :
-
European journal of biochemistry [Eur J Biochem] 1992 Jul 01; Vol. 207 (1), pp. 81-8. - Publication Year :
- 1992
-
Abstract
- Maltodextrin glycosyltransferase (4-alpha-glucanotransferase) of the extremely thermophilic ancestral bacterium Thermotoga maritima has been purified from an Escherichia coli clone expressing the corresponding T. maritima MSB8 chromosomal gene. T. maritima 4-alpha-glucanotransferase, an approximately 53-kDa monomeric enzyme, is the most thermophilic glycosyltransferase described to date. It retained more than 90% of its maximum activity at temperatures from 55 degrees C up to 80 degrees C. The proposed action modus is the transfer of 1,4-alpha-glucanosyl chains, thus resulting in the disproportionation of 1,4-alpha-glucans. It converted soluble starch, amylopectin, and amylose, thereby changing the iodine staining properties of these substrates. The addition of low-molecular-mass malto-oligosaccharides, which act as glucanosyl acceptor molecules, enhanced the reaction and resulted in the formation of a series of linear maltohomologues from two to more than nine glucose units in size. Use of either of the malto-oligosaccharides maltotetraose, maltopentaose, maltohexaose, or maltoheptaose as sole substrate also yielded linear maltohomologues. On the other hand, maltose and maltotriose were not disproportionated by 4-alpha-glucanotransferase, although both were good acceptors for glucanosyl transfer. Glucose did not function as an acceptor in transfer reactions. Glucose also never appeared as a reaction product. The chain length of glucanosyl segments transferred ranged from two to probably far more than six glucose residues. Comparison of the N-terminal amino acid sequence of 4-alpha-glucanotransferase with other published protein sequences revealed significant similarity to sequences near the N-termini of various eucaryotic maltases and bacterial cyclodextrin glycosyltransferases, suggesting its relatedness on the molecular level with other starch- and maltodextrin-converting enzymes.
- Subjects :
- Amino Acid Sequence
Base Sequence
Carbohydrates analysis
Chromatography, Gel
Chromatography, Ion Exchange
Enzyme Stability
Glycogen Debranching Enzyme System genetics
Glycogen Debranching Enzyme System metabolism
Gram-Negative Anaerobic Bacteria genetics
Hot Temperature
Kinetics
Molecular Sequence Data
Oligosaccharides pharmacology
Recombinant Proteins isolation & purification
Recombinant Proteins metabolism
Thermodynamics
Escherichia coli genetics
Glycogen Debranching Enzyme System isolation & purification
Gram-Negative Anaerobic Bacteria enzymology
Subjects
Details
- Language :
- English
- ISSN :
- 0014-2956
- Volume :
- 207
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- European journal of biochemistry
- Publication Type :
- Academic Journal
- Accession number :
- 1628664
- Full Text :
- https://doi.org/10.1111/j.1432-1033.1992.tb17023.x