[Cloning and expression of caiDE genes in E. coli BL21(DE3)]

The caiDE genes for carnitine racemase and its relative factor were cloned into pUC18 from the chromosomal DNA of E. coli MC4100 by shot-gun approach and have been verified by sequence analysis. The target plasmid was named as pJX393 and subcloned to form a transcription plasmid pDSW2. After its transformation into BL21(DE3) strain and induction by IPTG, the recombinant strain containing pDSW2 expressed two apparent protein bands on SDS-PAGE, whose molecular weight were 30 kD and 24 kD individually.