Effect of Adenosine on Methionyl‐tRNA Synthetase

The methionyl‐tRNA synthetase activities were shown to be inhibited by adenosine. In the ATP⇋PPi exchange, and in the hydroxamate reactions, the inhibition was competitive with respect to ATP and uncompetitive with respect to L‐methionine. In the methionine transfer reaction, inhibition patterns are more complicated, however the inhibition tends to be competitive with respect to ATP at high methionine concentration. The inhibition by adenosine of the ATP⇋PPi exchange reaction has been observed for several aminoacyl‐tRNA synthetases (seryl‐, cysteyl‐, isoleucyl‐, valyl‐, phenylalanyl‐, methionyl‐ and trypsin‐modified methionyl‐tRNA synthetases). However under standard conditions the degree of inhibition varies from one enzyme to the other.