23S rRNA (guanosine<sup>2251</sup>-2'-O)-methyltransferase (, rlmB (gene), yifH (gene)) is an enzyme with systematic name S-adenosyl-L-methionine:23S rRNA (guanosine<sup>2251</sup>-2'-O-)-methyltransferase. This enzyme catalyses the following chemical reaction
The enzyme catalyses the methylation of guanosine<sup>2251</sup>.