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Bending of the helical axis

Title SOLUTION STRUCTURE OF THE SPECIFIC DNA COMPLEX OF THE ZINC C DNA BINDING DOMAIN OF THE ERYTHROID TRANSCRIPTION FACTOR GA MULTIDIMENSIONAL NMR
PDB code 1GAU   (PDB summary)
NDB code 1GAU (NDB atlas)
Duplex length 8 base pairs
Protein Erythroid transcription factor GATA-1, Transcription factor, DNA binding domain: Cys4 zinc finger, divers

Table 1.   Bending parameters determined with the program ARC_FIT.  
The curvilinear helical axis is calculated with CURVES, and bending of this axis is analysed with ARC_FIT. This program allows to fit a straight line, a plane, an arc, a kinked line, and a double kinked line to the helical axis. Good fits are indicated by low values of sigma2. An arc is fitted if there are at least 7 bp. A kinked line requires at least 8 bp, and the double kinked line requires at least 13 bp. The geometrical parameters are given for all models fitted, but they characterize the shape of the helical axis only if the fit is good. See Help for further explanations.

 Model      sigma2 / Å2   Geometrical parameters 
 Plane  0.025  
 Straight line (x-axis) 0.169  
 Arc  0.214 Radius of curvature:  r = 141 Å
 Kinked line  0.264 Kink angle:  alpha = 8°
 Lengths of straight segments:  l1 = 3 bp,  l2 = 5 bp