Sodium salt, fiber diffraction from

Figure 2. Fiber diffraction from the sodium salt of polycytidylic acid recorded on a flat film perpendicular to the indicident x-ray beam. The fiber was at a 75° angle to the beam to permit the meridional diffraction on layer line 6 to be recorded. The lattice is trigonal with a = b — 2.32 nm c = 1.86 nm. The molecules are...

Figure 3. Fiber diffraction from a statistically disordered fiber of the sodium salt of poly d(GC) poly d(GC). The molecules in this structure form an unusual left-handed DNA duplex in which the dinucleotide pCpG is the molecular asymmetric unit. The unit cell is trigonal with a = b = 1.91 nm c = 4.35 nm. The space group is probably P226s. The molecular symmetry is itself 226s, and the statistical structure arises from a random choice of a molecular diad to a point along a particular direction.

Figure 6. X-ray fiber diffraction pattern obtained (in conjunction with Dr. H. Chanzy) from an oriented film oj the sodium salt oj Klebsiella K63...

Figure 15. X-ray fiber diffraction pattern obtained from an oriented film of the sodium salt of Klebsiella K8. It is evident that there is a slight perturbation from perfect four-fold symmetry giving rise to some weaker forbidden meridional...

To form nucleoproteins, the basic groups of the arginine combine with the phosphorus residues of DNA. When protamines are allowed to recombine with DNA in the presence of sodium salts, a nucleopro-tein appears that has properties very similar to nucleoproteins extracted from sperm head. Under appropriate conditions, these nucleoproteins can be precipitated in the form of fibers that can then be examined by X-ray diffraction. 

Fig. 7a c. The Raman spectra of (a) the A and (b) the B genus forms observed in fibers of DNA. The Raman spectra were obtained from a fiber of the sodium salt of calf thymus DNA at (a) 92% and (b) 75% relative humidity. Conversion between the two forms is completely reversible with changing humidity [72E1]. The conformation of the DNA in the fibers was determined from their X-ray fiber diffraction patterns [ 75E1]. (c) The Raman spectrum of the C-genus double helix of DNA observed from the fiber of the lithium salt of calf thymus DNA at 32% relative humidity [72E1]. 

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