title: Difference between Biological Activities and Secondary Structures of Expression Product of atpE Gene from Broad Bean and Maize Chloroplast.
abstract: The chloroplast atpE genes from broad bean and maize were overexpressed in E.coli, respectively. After proper refolding and purification, two types of epsilon-subunit proteins with biological activity were obtained. When reconstituted with CF(1)(-epsilon)from different chloroplast ATPase, the effects of the reconstructed epsilon-subunit protein of maize CF(1) to the Ca(2+)-ATPase activity of epsilon-deficient CF(1) and to the proton leakage through CF(0) were markedly stronger than that of broad bean CF(1). It was also observed that the enhancing effect of maize epsilon-subunit protein to the chloroplast photophosphorylation activity was greater than that of broad bean epsilon-subunit protein. The results indicate that (1)the inhibition of epsilon-subunit is closely related to the its affinity with other parts of CF(1) (2)both functions of epsilon-subunit as inhibitor of ATPase and as proton pathway are closely linked. The circular dichroism was performed to show the differences in their secondary structure of these epsilon-subunit proteins based on the deduced primary sequences. Unconstrained analysis of the CD spectrum for the maize epsilon-subunit protein gave 22.6% alpha-helix, 30.6% beta-sheet, 9.3% beta-turn, and 37.7% unordered structure and 31.4%alpha-helix, 22.3% beta-sheet, 13.8% beta-turn, and 32.4% unordered structure for the epsilon-subunit from broad bean.
authors.affiliation: Shanghai Institute of Plant Physiology, Chinese Academy of Sciences,Shanghai 200032,China. wjm@iris.sipp.ac.cn
authors.forename: Da-Fu
authors.initials: DF
authors.lastname: Wang
authors.forename: Jia-Mian
authors.initials: JM
authors.lastname: Wei