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Title

Calcium-binding affinity and calcium-enhanced activity of Clostridium thermocellum endoglucanase D.

Authors
Chauvaux, Sylvie
Beguin, Pierre
Aubert, Jean-Paul
Bhat, K Mahalingeshwara
Gow, Laura A
Wood, Thomas M
Published in Biochemical Journal. 1990, vol. 265, no. 1, p. 261-5
Abstract Clostridium thermocellum endoglucanase D (EC 3.2.1.4: EGD), which is encoded by the celD gene, was found to bind Ca2+ with an association constant of 2.03 x 10(6) M-1. Ca2+ stimulated the activity of EGD towards swollen Avicel by 2-fold. In the presence of Ca2+, the Kd of the enzyme towards p-nitrophenyl-beta-D-cellobioside and carboxymethylcellulose was decreased by 4-fold. Furthermore, Ca2+ increased the half-life of the enzyme at 75 degrees C from 13 to 47 min. Since the 3' sequence of celD encodes a duplicated region sharing similarities with the Ca2+-binding site of several Ca2+-binding proteins, a deleted clone was constructed and used to purify a truncated form of the enzyme which no longer contained the duplicated region. The truncated enzyme was very similar to EGD expressed from the intact gene with respect to activity, Ca2(+)-binding kinetics and Ca2+ effects on substrate binding and thermostability. Thus the latter parameters do not appear to be mediated through the duplicated conserved region.
Keywords Amino Acid SequenceCalcium/metabolismCellulase/genetics/metabolismClostridium/enzymology/geneticsElectrophoresis, Polyacrylamide GelMolecular Sequence DataPlasmidsSequence Homology, Nucleic Acid
Identifiers
PMID: 2302168
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Research group Calipho (80)
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CHAUVAUX, Sylvie et al. Calcium-binding affinity and calcium-enhanced activity of Clostridium thermocellum endoglucanase D. In: Biochemical Journal, 1990, vol. 265, n° 1, p. 261-5. https://archive-ouverte.unige.ch/unige:36237

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Deposited on : 2014-05-02

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