X-ray Diffraction Studies of Ring Crystals obtained for d(CACGCG).d(CGCGTG): Stage (iv) Hexagonal rings
Ring crystals of oligonucleotides: Growth stages and X-ray diffraction studies
1mM DNA, 75mM sodium cacodylate trihydrate buffer (pH 7.0), 0.5mM cobalt hexammine chloride, 0.75mM spermine, equilibrated against 50% methyl pentane diol (MPD) , VAPOR DIFFUSION, HANGING DROP, temperature 293K
The 3ULM structure is of stage (ii) in the ring crystal formation seen in oligonucleotide.
The 3ULN structure is of stage (iii) in the ring crystal formation seen in oligonucleotide.
chemically synthesized by M/s Microsynth
THE ACTUAL DNA SEQUENCE FOR THE THIS STUDY IS D(CACGCG).(CGCGTG)
Z-type DNA tetranucleotide built using InsightII
THE DNA OLIGONUCLEOTIDE HAS SIX BASE PAIRS (D(CACGCG).D(CGCGTG)) AND FORMS THE Z-TYPE DOUBLE HELICAL STRUCTURE. THE STRUCTURE HAS STATISTICAL DIS-ORDER AND THE ASYMMETRIC UNIT CONTAINS A TETRAMERIC DUPLEX WHICH COULD STAND FOR EITHER CPGPCPG/CPGPCPG OR CPAPCPG/CPGPTPG OR CPGPCPA/TPGPCPG. DUE TO DISORDER, THE TETRANUCLEOTIDE WAS CONSTRUCTED AS TPGPTPG/TPGPTPG IN WHICH THE C5 METHYL GROUP OF THYMINE WAS ASSIGNED OCCUPANCY OF 1/6 AND N2 OF GUANINE WAS ASSIGNED OCCUPANCY OF 5/6.
Z-type DNA double helix, ring crystal, crystal morphology, DNA