Crystallographic Analysis of the Interaction of Cupric Ion with Ribonuclease S

摘要: Abstract The binding of Cu(II) to crystalline RNase-S, RNase-E, and 41-DNP-RNase-S in the presence 3 m (NH4)2SO4 has been investigated crystallographically. At pH 5.5, with 0.1 acetate present as buffer, seven sites were detected on three which are intermolecular. intramolecular occur near His-119, His-105, Glu-86, a sulfate ion bound at active site, have fractional occupancies concentration 100 mm 1.07 ± 0.10, 0.79 0.42 0.09, 0.33 respectively. intermolecular amino terminus S-peptide, S-protein, Asp-53. Cu(II), these 1.25 0.68 0.12, 0.31 modes RNase-S RNase-E essentially identical. On other hand, site is absent dinitrophenylated enzyme there minor changes positions, occupancies, or temperature factors Glu-86 S-protein. 7.0, 0.67 0.3 ethanolamine, all decrease, although nitrogen ligands decrease less than those oxygen ligands. ion, Asp-53 appear be unoccupied, but new Asp-121, possibly involving appears. In 3'-CMP 5.5 enhanced 20% no change its mode could A resolution.