truncated mutant of human PDE4B2

Abstract:

Objective：To compare the expression，affinity purification and enzyme kinetics against representative inhibitors of full-length human phsphodiesterase 4B2 fused with 6His-SUMO on N-terminus（SF-hPDE4B2） and its 152-528aa truncate fused with 6His-SUMO on N-terminus（ST-hPDE4B2），to reveal the superiority of ST-hPDE4B2 over SF-hPDE4B2 as the target for high-throughput screen of hPDE4B2 inhibitors as potential anti-inflammatory agents. Methods：The two fusion proteins were expressed in Escherichia coli BL 21（DE3） and purified through Ni2+-NTA；phsphodiesterase activities were measured via alkaline phosphatase-coupled malachite green assay of phosphate in high-throughput mode. Results：After affinity purification，ST-hPDE4B2 exhibited spe－cific activity nearly 40-fold higher and activity yield over 100-fold higher than SF-hPDE4B2；SDS-PAGE and Western blot of 6His tag supported that there were a lot of polypeptides degraded in both of the purified fusion proteins. Inhibition constants of （R）-Rolipram and papaverine indicated that SF-hPDE4B2 mainly existed in the high-affinity state while ST-hPDE4B2 appeared princi－pally in the low-affinity state for （R）-Rolipram. Conclusion：ST-hPDE4B2 may have some advantages over SF-hPDE4B2 as the tar－get for the screening of inhibitors as potential anti-inflammatory agents.