STRUCTURE OF RUBREDOXIN AT 1.2 A RESOLUTION

Structural details of the model of Clostridium pasteurianum rubredoxin are presented, based on the refined model at 1.2 Å resolution. The molecule contains no extensive regions of pleated-sheet or helical structure. Regular secondary structure consists primarily of residues 3 to 7, 11 to 13 and 48 to 52 in a small region of pleated-sheet; and residues 14 to 18, 19 to 23, 29 to 33 and 45 to 49 in 310 helical corners. Interbond angles in the helical corners average as much as 10 ° greater than normally accepted values and a number of the peptide groups deviate significantly from planarity. Rubredoxin has a pronounced asymmetry in the distribution of charged groups on its surface. This would lead to highly favored molecular orientations when the protein interacts with other charged molecules. Bond lengths in the iron-sulfur complex range from 2.24 å to 2.33 Å, and bond angles range from 104 ° to 114 °. © 1979.