doiSerbia

A highly inducible β-galactosidase from Enterobacter sp.

Shaikhan Bestoon Ahmed (Department of Biology, Faculty of Science, Dicle University, Diyarbakır, Turkey)
Güven Kemal (Department of Molecular Biology and Genetics, Faculty of Science, Dicle University, Diyarbakır, Turkey)
Bekler Fatma Matpan (Department of Biology, Faculty of Science, Dicle University, Diyarbakır, Turkey)
Acer Ömer (Department of Biology, Faculty of Science, Dicle University, Diyarbakır, Turkey)
Güven Reyhan Gül (Science Teaching Section, Education Faculty, Dicle University, Diyarbakir, Turkey)

Enterobacter sp. 3TP2A isolated from a petroleum station was found to produce a novel, highly inducible mesophilic intracellular β-galactosidase in the presence of lactose up to 76.5 U mg-1. The enzyme was purified to 17.3- -fold after gel permeation chromatography with a yield of approximately 11 %. The optimum pH and temperature values of the purified enzyme were found to be 8.0–9.0 and 35 °C, respectively. The molecular weight of the enzyme was approx. 60 kDa with a single band by both SDS-PAGE and native-PAGE, and estimated by gel filtration chromatography. The enzyme was inhibited by Zn2+ and EDTA, while Cu2+ had strong inhibitory effect even at low concentrations. Activation by Mg2+ and inhibition by EDTA show that the enzyme is metal- -dependent or a metalloenzyme. The enzyme was slightly activated by 2-mercaptoethanol, while slightly inhibited by iodoacetamide. On the other hand, PCMB inhibited the enzymatic activity to a great extent, whereas it was completely inhibited by N-ethylmaleimide. The Vmax and Km values were calculated as 0.701 μmol min-1 and 0.104 mM, respectively. The results indicated that the β-galactosidase Enterobacter sp. 3TP2A might well be a good candidate for use in biotechnology, particularly in the area of environment and health.

Keywords: β-galactosidase, Enterobacter, purification, characterization, inhibition