Crystallization and preliminary X-ray diffraction analysis of spermidine synthase from Helicobacter pylori.

Polyamines, such as putrescine, spermidine and spermine, are essential for the regulation of cell proliferation and differentiation in most organisms. Spermidine synthase catalyzes the transfer of the aminopropyl group from decarboxylated S-adenosylmethionine to putrescine in the biosynthesis of spermidine. In this study, spermidine synthase of Helicobacter pylon has been overexpressed in Escherichia coli and purified. Two kinds of spermidine synthase crystals were obtained. One belongs to the monoclinic P21 space group, with unit-cell parameters a = 62.78, b = 58.24, c = 74.28 Å, β = 90.9°, and the other belongs to the orthorhombic C2221 space group, with unit-cell parameters a = 100.43, b = 128.55, c = 143.60 Å. [ABSTRACT FROM AUTHOR]