tRNA pseudouridine<sup>38/39</sup> synthase (, Deg1, Pus3p, pseudouridine synthase 3) is an enzyme with systematic name tRNA-uridine<sup>38/39</sup> uracil mutase. This enzyme catalyses the following chemical reaction
The enzyme from Saccharomyces cerevisiae is active only towards uridine<sup>38</sup> and uridine<sup>39</sup>.