Biochemical Characterization of A Novel Thermophilic Esterase Isolated from Shewanella sp F88

The main objective of this study was to purify and characterize an esterase from shewanella sp f88. the enzyme was purified 41-fold and an overall yield of 21 %, using a two-step procedure, including ammonium sulfate precipitation and q-sepharore chromatography. molecular weight of the enzyme was 62.3 kda according to sds-page data. the enzyme showed an optimum activity at ph 6.5 and 58 ?c. evolution of substrate specificity demonstrated that this thermostable enzyme had the highest activity towards para-nitrophenol acetate (pnpa, c2). michaelis-menten constant (km) and maximum velocity (vmax) of pnpa-hydrolyzing reaction were 12.6 mm and 550 u.mg-1, respectively. enzyme activity was declined in the presence of metal ions (2 and 5 mm), including fe2+, ca2+, cu2+, zn2+, mg2+ and mn2+. the half-lives of purified esterase was 70 and 31 min at 60 °c and 80 °c, respectively. in conclusion, the enzyme is a novel thermostable lipolytic enzyme characterized from shewanella species.