sentences:  The reaction of orotic acid (orotate) to orotidylate is catalyzed by orotate phophoribosyltransferase with the cofactor PRPP, which is a cofactor commonly used for nucleotide synthesis.It transfers pyrophosphoryl groups very favorably with a ΔG of -8.3 + 0.5 kcal/mol.Two main interactions attract PRPP to assist orotate phophoribosyltransferase in this reaction.