Functional characterization of a thermostable methionine adenosyltransferase from Thermus thermophilus HB27

MATTt (a thermostable methionine adenosyltransferase from Thermus thermophilus HB27) was overexpressed in Escherchia coli and purified using Ni-NTA affinity column. The enzymatic activity of MATTt was investigated in a temperature range from 30 °C to 90 °C, showing that MATTt exhibited a high enzymatic activity and good thermostability at 80 °C. Circular dichroism spectra reveals that MATTt contains high portion of β-sheet structures contributing to the thermostability of MATTt. The kinetic parameter, K m is 4.19 mmol/L and 1.2 mmol/L for ATP and methionine, respectively. MATTt exhibits the highest enzymatic activity at pH 8. Cobalt (Co2+) and zinc ion (Zn2+) enhances remarkably the activity of MATTt compared to the magnesium ion (Mg2+). All these results indicated that the thermostable MATTt has great potential for industry applications.