AKR1C3 also known as Aldo-keto reductase family 1 member C3 isoform 1, is a member of the aldo-keto reductase superfamily which catalyzes the conversion of aldehydes and ketones to their corresponding alcohols by utilizing NADH and/or NADPH as cofactors. This enzyme catalyzes the reduction of prostaglandin (PG) D2, PGH2 and phenanthrenequinone (PQ), and the oxidation of 9 alpha, 11 beta-PGF2 to PGD2. It may play an important role in the pathogenesis of allergic diseases such as asthma, and may also have a role in controlling cell growth and differentiation. Recombinant human AKR1C3 protein was expressed in E.coli and purified by using conventional chromatography techniques.