Reversible thermal inactivation and conformational states in denaturant guanidinium of a calcium-dependent peroxidase from Euphorbia characias

The changes in the heme environment and overall structure occurring during reversible thermal inactivation and in denaturant guanidinium of Euphorbia characias latex peroxidase (ELP) were investigated in the presence and absence of calcium ions. Native active enzyme had an absorption spectrum typica...

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Bibliographic Details
Published in:International journal of biological macromolecules 2005-12, Vol.37 (4), p.205-211
Main Authors: Mura, Anna, Longu, Silvia, Padiglia, Alessandra, Rinaldi, Andrea C., Floris, Giovanni, Medda, Rosaria
Format: Article
Language:English
Subjects:
Calcium - chemistry
Enzyme Activation
Enzyme Stability
Euphorbia - enzymology
Euphorbia characias
Guanidine - chemistry
Heme - chemistry
Kinetics
Peroxidase
Peroxidase - chemistry
Peroxidase - isolation & purification
Plant Proteins - chemistry
Plant Proteins - isolation & purification
Protein Conformation
Protein Denaturation
Temperature
Thermal inactivation
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Summary:The changes in the heme environment and overall structure occurring during reversible thermal inactivation and in denaturant guanidinium of Euphorbia characias latex peroxidase (ELP) were investigated in the presence and absence of calcium ions. Native active enzyme had an absorption spectrum typical of a quantum-mixed spin ferric heme protein. After 40 min at 60 °C ELP was fully inactivated showing the spectroscopic behavior of a pure hexacoordinate low-spin protein. The addition of Ca 2+ to the thermally inactivated enzyme restored its native activity and its spectroscopic features, but did not increase the stability of the protein in guanidinium. It is concluded that, in Euphorbia peroxidase, Ca 2+ ion play a key role in conferring structural stability to the heme environment and in retaining active site geometry.
ISSN:0141-8130
1879-0003
DOI:10.1016/j.ijbiomac.2005.10.010