Porphobilinogen synthase (formerly 5-aminolevulinic acid dehydratase, EC 188.8.131.52) was purified 7,405-fold from an aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh 114. The molecular weight of the enzyme was determined to be 260,000 by Sephadex G-200 gel filtration. The enzyme had a single pH optimum at 8.0 and showed no requirement for metal ion and thiol compound for its maximum activity. The Km value for 5-aminolevulinic acid was 0.29 mM. 4,5-Dioxovaleric acid and levulinic acid were found to be competitive inhibitors of the enzyme, with Ki values of 0.65 and 0.80 mM, respectively. The enzyme was extremely labile in acidic pH and almost completely lost its activity within 1 h at pH 6.0 and 30°C. This Erythrobacter enzyme seems to be similar to the enzyme from the anaerobic photosynthetic bacterium Rhodobacter capsulatus in its molecular and catalytic properties.
|Number of pages||6|
|Journal||Plant and Cell Physiology|
|Publication status||Published - Jul 1988|
All Science Journal Classification (ASJC) codes
- Plant Science
- Cell Biology