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

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 degreesC, respectively. TMAOase was stable to heat treatment up to 50 degreesC and the activation energy was calculated to be 30.5 U mol(-1) K-1. Combined cofactors (FeCl2, ascorbate and cysteine) were required for full activation. FeCl2 exhibited a higher stimulating effect on TMAOase activity than FeCl3. 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 mumol min(-1) and was able to concert TMAO to dimethylamine (DMA) and formaldehyde. The molecular mass of enzyme was estimated to be 128 kDa based on activity staining. (C) 2003 Elsevier Science Inc. All rights reserved.