Article (Published version) (1.2 MB) - Free access
Calcium-binding affinity and calcium-enhanced activity of Clostridium thermocellum endoglucanase D.
|Published in||Biochemical Journal. 1990, vol. 265, no. 1, p. 261-5|
|Abstract||Clostridium thermocellum endoglucanase D (EC 22.214.171.124: 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 Sequence — Calcium/metabolism — Cellulase/genetics/metabolism — Clostridium/enzymology/genetics — Electrophoresis, Polyacrylamide Gel — Molecular Sequence Data — Plasmids — Sequence Homology, Nucleic Acid|
|Research group||Calipho (80)|
|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|