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Activation Function of Chloroperoxidase in the Presence of Metal Ions at Elevated Temperature from 25 to 55°C
Author(s) -
GAO Qiang,
JIANG Yucheng,
GAO Xiaoqin,
HU Mancheng,
LI Shuni,
ZHAI Quanguo
Publication year - 2009
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.200990215
Subject(s) - chemistry , catalysis , substrate (aquarium) , metal , metal ions in aqueous solution , ion , transition metal , base (topology) , inorganic chemistry , nuclear chemistry , organic chemistry , mathematical analysis , oceanography , geology , mathematics
The investigation and comparison of chlorination activity of chloroperoxidase (CPO) from Caldariomyces fumago in metal ion solutions to those in pure buffer indicated that CPO could be effectively activated by some alkaline‐earth metals and transition metals. The obtained maximum relative activity of CPO was 1.33 time at 75 µmol·L −1 Ca 2+ , 1.37 time at 90 µmol·L −1 Mg 2+ , 1.34 time at 90 µmol·L −1 Ni 2+ , and 1.27 time at 105 µmol·L −1 Co 2+ at 25°C. Moreover, the CPO stability against temperature was improved in the presence of the above metal ions. At 55°C, CPO could retain only about 40% of activity whereas 75% and 81% of activity were maintained in Mg 2+ and Ca 2+ media, respectively. It was suggested that the metal ions bind to the acid‐base catalytic groups Glu183, His105 and Asp106 around the active site of CPO, and activate CPO by both an enrichment of substrate concentration and the conformational change of CPO, which are favorable to the substrate access. The analysis of kinetic parameters indicated that the activation was mainly due to an increase in k cat values. The affinity and specificity of CPO to substrates were also improved in these metal ion media. The results in this work are promising in view of industrial applications of this versatile biological catalyst.