The catalytic behavior of a membrane-bound lipolytic enzyme (MBL-Enzyme) from the microalgae Nannochloropsis oceanica CCMP1779 was investigated. The biocatalyst showed maximum activity at 50 degrees C and pH 7.0, and was stable at pH 7.0 and temperatures from 40 to 60 degrees C. Half-lives at 60 degrees C, 70 degrees C and 80 degrees C were found 866.38, 150.67 and 85.57 mM respectively. Thermal deactivation energy was 68.87 kJ mol(-1). The enzyme's enthalpy (Delta H*), entropy (Delta S*) and Gibb's free energy (Delta G*) were in the range of 65.86-66.27 kJ mol(-1), 132.38-140.64 J mol K-1 and 107.80-115.81 kJ mol(-1), respectively. Among p-nitrophenyl esters of fatty acids tested, MBL-Enzyme exhibited the highest hydrolytic activity against p-nitrophenyl palmitate (pNPP). The K m and V-max values were found 0.051 mM and of 0.054 mmole pNP mg protein(-1) mM(-1), respectively with pNPP as substrate. The presence of Mn(2+)increased lipolytic activity by 68.25%, while Fe3+ and Cu2+ ions had the strongest inhibitory effect. MBL-Enzyme was stable in the presence of water miscible (66% of the initial activity in ethanol) and water immiscible (71% of the initial activity in n-octane) solvents. Myristic acid was found to be the most efficient acyl donor in esterification reactions with ethanol. Methanol was the best acyl acceptor among the primary alcohols tested.