MW: 55 Kda. Cytochrome P450 2C19 (CYP2C19, EC 1.14.14.1) is a member of the cytochrome P450 monooxidase (CYP) family of microsomal xenobiotic metabolism enzymes. CYPs are membrane-bound hemeproteins responsible for Phase I biotransformation reactions, in which lipophilic drugs and other xenobiotic compounds are converted to more hydrophilic products to facilitate excretion from the body. CYP2C19 is primarily expressed in liver and intestinal tissue and catalyzes oxidation of neutral or weakly basic lipophilic molecules with 2-3 hydrogen bond donor/acceptor sites. Isoforms of the CYP2C subfamily are responsible for metabolism of nearly 20% of all small molecule drugs commonly used by humans. Polymorphisms in the human CYP2C19 gene have been implicated in clinical drug/drug interactions involving widely-prescribed drugs, including proton pump inhibitors, antiplatelet agents and anticonvulsants. BioVision's EZCyp(tm) 2C19 is a permeabilized and stabilized dried yeast powder preparation containing recombinant human CYP2C19 and recombinant human P450 NADPH oxidoreductase co expressed in the same preparation.