Partial purification and characterization of trimethylamine- N-oxide demethylase from lizardfish kidney

Abstract

Trimethylamine- N-oxide demethylase (TMAOase) from lizardfish ( Saurida micropectoralis) was partially purified by acidification and diethylaminoethyl (DEAE)-cellulose chromatography. The enzyme was purified 82-fold with a yield of 65.4%. The optimum pH and temperature were 7.0 and 50 °C, respectively. TMAOase was stable to heat treatment up to 50 °C and the activation energy was calculated to be 30.5 kJ mol −1 K −1. Combined cofactors (FeCl 2, ascorbate and cysteine) were required for full activation. FeCl 2 exhibited a higher stimulating effect on TMAOase activity than FeCl 3. At concentration less than 2 mM, ascorbate was more stimulatory to the activity than cysteine. The activity was tolerant of NaCl concentration up to 0.5 M. The enzyme had a K m for TMAO of 16.2 mM and V max of 0.35 μmol min −1 and was able to convert TMAO to dimethylamine (DMA) and formaldehyde. The molecular mass of enzyme was estimated to be 128 kDa based on activity staining.