Abstract
Purified trimethylamine-N-oxide demethylase (TMAOase) from walleye pollack muscle is a thermostable protein that was not inactivated after heating at 80°C for 30 min. The heated enzyme was electrophoresed in the same manner as fornative enzyme. Circular dichroism (CD) spectra for purified enzyme changed reversibly in the temperature range of 10-80°C. As the enzyme was still active at 80°C, the CD spectral change did not directly relate to enzyme activity. TMAOase activity inthe myofibrillar fraction decreased sharply above 30°C, but was extracted and recovered from the heated myofibrillar fraction, suggesting that the activity seemed to be interrupted and apparently inactivated due to the thermal alteration of myofibrillar proteins or some unknownfactors. The complicated profile found in dimethylamine (DMA) formation from trimethylamine-N-oxide (TMAO) in walleye pollack muscle during heating consisted of both enzymic and non-enzymic processes. Most DMA was produced enzymatically below 40°C and interrupted above 40°C. Therefore, DMA and trimethylamine was formednon-enzymatically at high temperatures regardless of the presence of native enzyme. A new, simple and easy purification method was proposed based on the thermostable nature of the enzyme.
