Occurrence and some properties of trimethylamine-N-oxide demethylase in myofibrillar fraction from walleye pollack muscle

The study describes the occurrence and characterization of an enzyme in the myofibrillar fraction from walleye pollack muscle which is responsible for the reduction of trimethylamine-N-oxide to dimethylamine and formaldehyde. The enzyme, trimethylamine-N-oxide demethylase (TMAOase), activity was optimal at pH 7.0-7.5 and was inactivated above 30 degrees C. The apparent activation energy was 30.7 and 55.9 kJ.mol(-1).deg(-1) above 15 degrees C and in the range of 0-15 degrees C, respectively. Above 0 degrees C, dimethylamine formation increased depending on the rise in temperature, although below 0 degrees C, it slightly increased at -20 degrees C than at 0 and -4 degrees C. The NaCl reduced TMAOase activity at higher concentrations. The enzyme in the myofibrillar fraction required a cofactor system containing Fe2+, ascorbate, and cysteine for full activation.