:TRNA pseudouridine38/39 synthase

{{Infobox enzyme

| Name = tRNA pseudouridine^38/39 synthase

| EC_number = 5.4.99.45

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| GO_code =

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tRNA pseudouridine^38/39 synthase ({{EnzExplorer|5.4.99.45}}, Deg1, Pus3p, pseudouridine synthase 3) is an enzyme with systematic name tRNA-uridine^38/39 uracil mutase.{{cite journal | vauthors = Lecointe F, Simos G, Sauer A, Hurt EC, Motorin Y, Grosjean H | title = Characterization of yeast protein Deg1 as pseudouridine synthase (Pus3) catalyzing the formation of psi 38 and psi 39 in tRNA anticodon loop | journal = The Journal of Biological Chemistry | volume = 273 | issue = 3 | pages = 1316–23 | date = January 1998 | pmid = 9430663 | doi = 10.1074/jbc.273.3.1316 | doi-access = free | url = https://hal.inrae.fr/hal-02699150/file/1998_Lecointe_Journal%20of%20Biological%20Chemistry_1.pdf }}{{cite journal | vauthors = Chen J, Patton JR | title = Pseudouridine synthase 3 from mouse modifies the anticodon loop of tRNA | journal = Biochemistry | volume = 39 | issue = 41 | pages = 12723–30 | date = October 2000 | pmid = 11027153 | doi = 10.1021/bi001109m }} This enzyme catalyses the following chemical reaction

: tRNA uridine^38/39 $\backslash rightleftharpoons$ tRNA pseudouridine^38/39

The enzyme from Saccharomyces cerevisiae is active only towards uridine³⁸ and uridine³⁹.