<prompt> Which is true for glucuronidation:Water solubility is decreasedPhase II reactionPhase I reactionDone by CYP enzyme  <response>: Ans. b Phase II reactionRef: Harpers Biochemistry, 30 edn. pg. 586 thMETABOLISM OF XENOBIOTICS In phase 1, the major reaction involved is hydroxylation, catalyzed by enzymes mono-oxygenases or cytochrome P450s. The reactions are: Hydroxylation Deamination Dehalogenation Desulfuration Epoxidation Peroxygenation Reduction In phase 2, compounds produced in phase 1 are converted to various polar metabolites by conjugationwith glucuronic acid, sulfate, acetate, glutathione, or certain amino acids, or by methylation. The overall purpose of the two phases of metabolism of xenobiotics is to increase their water solubility polarity and thus excretion from the body.Glucuronidation: UDP Glucuronic acid is the glucuronyl donor, and a variety of glucuronosyl transferases, present in both the endoplasmic reticulum and cytosol, are the catalysts. Phase II reactions are: Glucuronidation: is probably the most frequent conjugation reaction. Sulfation Conjugation with Glutathione Acetylation Methylation 