Hydroxybenzoate decarboxylase EC

4-Hydroxybenzoate decarboxylase (EC 4.1.1.61) of anaerobe C. hydroxyben-zoicum was purified and characterized for the first time. ° It has an apparent molecular mass of 350 kDa and consists of six identical subunits of 57kDa. The temperature optimum for the decarboxylation is approximately 50°C, the optimum pH being 5.6-6.2. The activation energy for decarboxylation of 4-hydroxybenzoate is 65kJmor (20-37°C). The enzyme also catalyzes the decarboxylation of 

4-dihydroxybenzoate. The apparent and values for 4-hydroxybenzoate are 0.40mM and 3.3 x 10 min , and for 3,4-dihydroxybenzoate 1.2mM and 1.1 X 10 min , respectively, at pH 6.0 and 25°C. The enzyme activity was not influenced by the addition of biotin or avidin. Secondly, 4-hydroxybenzoate decarboxylase from an anaerobic co-culture, consisting of Clostridium-like strain and an unidentified strain, was purified and characterized.  

The occurrence of 4-hydroxybenzoate decarboxylase was also found in facultative anaerobic bacteria, E. cloacae P240, and the enzyme was purified and characterized. The activity of the cell-free extract of E. cloacae P240 was determined to be 13.7 ijumol min (mg protein) at 30°C, which was much higher than 

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