PMID: 23759Dec 1, 1977

Chemical modification of cellulase from Aspergillus niger

The Biochemical Journal
P L HurstM G Shepherd

Abstract

N-Bromosuccinimide completely inactivated the cellulase, and titration experiments showed that oxidation of one tryptophan residue per cellulase molecule coincided with 100% inactivation. CM-cellulose protected the enzyme from inactivation by N-bromosuccinimide. The cellulase was inhibited by active benzyl halides, and reaction with 2-hydroxy-5-nitrobenzyl bromide resulted in the incorporation of 2.3 hydroxy-5-nitrobenzyl groups per enzyme molecule; one tryptophan residue was shown to be essential for activity. Diazocarbonyl compounds in the presence of Cu2+ ions inhibited the enzyme. The pH-dependence of inactivation was consistent with the reaction occurring with a protonated carboxyl group. Carbodi-imide inhibited the cellulase, and kinetic analysis indicated that there was an average of 1 mol of carbodi-imide binding to the cellulase during inactivation. Treatment of the cellulase with diethyl pyrocarbonate resulted in the modification of two out of the four histidine residues present in the cellulase. The modified enzyme retained 40% of its original activity. Inhibition of cellulase activity by the metal ions Ag+ and Hg2+ was ascribed to interaction with tryptophan residues, rather than with thiol groups.

References

Feb 15, 1992·European Journal of Biochemistry·M R Bray, A J Clarke
Jun 3, 1985·European Journal of Biochemistry·A J Clarke, M Yaguchi
Jun 19, 2013·Protein Expression and Purification·Hui-Chang WangRuey-Shyang Hseu
Feb 11, 1999·Bioscience, Biotechnology, and Biochemistry·S AkibaH Kumagai
May 1, 1983·Biotechnology and Bioengineering·R F Boyer, M A Redmond
Apr 8, 2006·Physiological Reviews·Kensaku MoriMasahiro Yamaguchi

Related Concepts

Tryptophan
Histidine
Structure-Activity Relationship
Ions
Sulfhydryl Compounds
Imides
Oxidation
Carbodiimides
PMS-Tryptophan
Diethyl Pyrocarbonate

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