This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Van Rijssel, M Articles by Hansen, T A Search for Related Content PubMed PubMed Citation Articles by Van Rijssel, M Articles by Hansen, T A Agricola Articles by Van Rijssel, M Articles by Hansen, T A

 Previous Article  |  Next Article 

Appl Environ Microbiol. 1993 March; 59(3): 828-836

Isolation and characterization of an extracellular glycosylated protein complex from Clostridium thermosaccharolyticum with pectin methylesterase and polygalacturonate hydrolase activity.

Department of Microbiology, University of Groningen, The Netherlands.

ABSTRACT

An extracellular protein complex was isolated from the supernatant of a pectin-limited continuous culture of Clostridium thermosaccharolyticum Haren. The complex possessed both pectin methylesterase (EC 3.1.1.11) and exo-poly-alpha-galacturonate hydrolase (EC 3.2.1.82) activity and produced digalacturonate from the nonreducing end of the pectin chain. The protein consisted of 230- and 25-kDa subunits. The large subunit contained 10% (wt/wt) sugars (N-acetylgalactosamine and galactose). Under physiological conditions both activities acted in a coordinated manner: the ratio between methanol and digalacturonate released during degradation was constant and equal to the degree of esterification of the pectin used. Prolonged incubation of the enzyme with pectin led to a nondialyzable fraction that was enriched in neutral sugars, such as arabinose, rhamnose, and galactose; the high rhamnose/galacturonic acid ratio was indicative of hairy region-like structures. The smallest substrate utilized by the hydrolase was a tetragalacturonate. Vmax with oligogalacturonates increased with increasing chain length. The Km and Vmax for the polygalacturonate hydrolase with citrus pectate as a substrate were 0.8 g liter-1 and 180 mumol min-1 mg of protein-1, respectively. The Km and Vmax for the esterase with citrus pectin as a substrate were 1.2 g liter-1 and 440 mumol min-1 mg of protein-1, respectively. The temperature optima for the hydrolase and esterase were 70 and 60 degrees C, respectively. Both enzyme activities were stable for more than 1 h at 70 degrees C. The exo-polygalacturonate hydrolase of Clostridium thermosulfurogenes was partially purified while the methylesterase was also copurified.

This article has been cited by other articles:

• Mutter, M., Beldman, G., Pitson, S. M., Schols, H. A., Voragen, A. G.J. (1998). Rhamnogalacturonan alpha -d-Galactopyranosyluronohydrolase . An Enzyme That Specifically Removes the Terminal Nonreducing Galacturonosyl Residue in Rhamnogalacturonan Regions of Pectin. Plant Physiol. 117: 153-163 [Abstract] [Full Text]