K. Isobe et N. Wakao, PURIFICATION AND SOME PROPERTIES OF A THERMOSTABLE ACID ESTERASE FROMACIDIPHILIUM SP. AIU-409, Journal of General and Applied Microbiology, 43(3), 1997, pp. 151-156
Extracellular and cell-bound esterases produced by Acidiphilium sp. AI
U 409 were homogeneously purified from culture broth and cells, respec
tively, and some properties were investigated. Both esterases more rap
idly hydrolyzed p-nitrophenyl acyl esters containing long-chain fatty
acids from C 8:0 to C 18:0 than those containing short-chain fatty aci
ds from C 2:0 to C 6:0. The Km values for p nitrophenyl long-chain fat
ty acid esters from C 8:0 to C 18:0 were approximately 1.3-1.5 mM. The
enzymes were stable at 50 degrees C for 2 days between pH 3.0 and 6.5
, and optimum pH and temperature were 5.0 and 70 degrees C, respective
ly. Enzyme activity was inhibited by phenylmethylsulfonyl fluoride and
SDS. The molecular mass of both enzymes was estimated to be approxima
tely 64 kDa by SDS-PAGE. The 23 amino acid sequence from the NH2-termi
nus was also the same in both enzymes. These results suggest that extr
acellular esterase might be composed of the same components as cell-bo
und esterase.