PURIFICATION AND CHARACTERIZATION OF A CARBOXYLESTERASE FROM PSEUDOMONAS SP KWI-56

An intracellular carboxylesterase from Pseudomonas sp. was overproduce d in E. coli, and purified to homogeneity by a combination of hydrogen bond chromatography, gel filtration, and hydrophobic interaction chro matography. Gel filtration and SDS-PAGE suggested that the purified en zyme consisted of two subunits of molecular mass of 28 kDa. Tts isoele ctric point was 5.9. The enzyme was thermolabile, and showed its maxim um activity at 22 degrees C (pH 7.5). Methyl propionate was hydrolyzed at the highest rate among the fatty acid methyl esters tested. PMSF, DFP, PCMB, and HgCl2 inhibited the enzyme markedly, suggesting that se rine and/or cysteine is in or near the active site.