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Issue 2, 2012
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Cu(II)- and disulfide bonds-induced stabilization during the guanidine hydrochloride- and thermal-induced denaturation of NAD-glycohydrolase from the venom of Agkistrodon acutus

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Abstract

NAD-glycohydrolase (AA-NADase) from Agkistrodon acutus venom is a unique multicatalytic enzyme with both NADase and AT(D)Pase-like activities. Among all identified NADases, only AA-NADase is a disulfide-linked dimer and contains Cu2+. Cu2+ and disulfide bonds are essential for its multicatalytic activity. In this study, the effects of Cu2+ and disulfide-bonds on guanidine hydrochloride (GdnHCl)- and thermal-induced unfolding of AA-NADase have been investigated by fluorescence, circular dichroism (CD) and differential scanning calorimetry (DSC). Cu2+ and disulfide bonds not only increase the free energy change during the GdnHCl-induced unfolding as determined by fluorescence, but also increase the overall enthalpy change and the transition temperature during the thermal-induced unfolding as determined by CD and DSC. The slope of the GdnHCl-induced unfolding curve at its midpoint and the heat capacity of thermal-induced unfolding are slightly affected by Cu2+ but significantly decrease after reduction of three disulfide-bonds. This work suggests that Cu2+ stabilizes the folded state by increasing the enthalpy of unfolding, while disulfide-bonds stabilize the folded state by increasing the enthalpy of unfolding and stabilizing the packing of hydrophobic residues. Thus both Cu2+ and disulfide bonds play a structural role in its multicatalytic activity.

Graphical abstract: Cu(ii)- and disulfide bonds-induced stabilization during the guanidine hydrochloride- and thermal-induced denaturation of NAD-glycohydrolase from the venom of Agkistrodon acutus

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Publication details

The article was received on 18 Aug 2011, accepted on 12 Oct 2011 and first published on 02 Nov 2011


Article type: Paper
DOI: 10.1039/C1MT00135C
Citation: Metallomics, 2012,4, 166-173
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    Cu(II)- and disulfide bonds-induced stabilization during the guanidine hydrochloride- and thermal-induced denaturation of NAD-glycohydrolase from the venom of Agkistrodon acutus

    L. Zhang, X. Xu, Z. Luo, Y. Zhang, D. Shen, L. Peng and J. Song, Metallomics, 2012, 4, 166
    DOI: 10.1039/C1MT00135C

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