中国生物工程杂志

DHCR24 can protect cells from apoptosis induced by oxidative stress, but the detail mechenism is unknow. Our previous data obtained from in vivo experiments shown that DHCR24 might scavenge intracellular H2O2. In this study, we examined whether DHCR24 could directly decompose H2O2. We constructed the 3 plasmids including pIVEX2.4a－DHCR24（Wild Type）, pIVEX2.4a-ORD(the C-terminal deletion mutant, 1-395, including entire putative oxidareductive domain), and pIVEX2.4a-CTR（232-516, lacking the ORD, but it contains the entire C-terminal region,which has no similarity to known protein domains..We syhthesized all the His-tagged DHCR24 and its mutant in E.coli by the RTS 500 systerm, and purified them by Ni column. When applied to the H2O2-scavenging assay, WT (1-516) exhibited significant scavenging activity, ORD (1-395) preserved the activity, whereas CTR (232-516) lost it, indicating the important role of ORD in H2O2 decomposition. To explore the physiological role of antioxidatic function of DHCR24, we investigated the cellular location of DHCR24 utilizing the double immunocytochemical staining. The results demonstrated the DHCR24 is localized to endoplasmic reticulum ( ER ), indicating that the location on the ER of DHCR24 might be involved in its antioxidatic activity.