Visualization of drug-nucleic acid interactions at atomic resolution. VI. Structure of two drug/ dinucleoside monophosphate crystalline complexes, ellipticine: 5-iodocytidylyl(3'-5')guanosine and 3,5,6,8-tetramethyl-n-methyl phenanthrolinium: 5-iodocytidylyl(3'-5')guanosine
Ellipticine and 3,5,6,8-tetramethyl-N-methyl phenanthrolinium (TMP) form complexes with the dinucleoside monophosphate, 5-iodocytidylyl(3'-5')guanosine (iodoCpG). These crystals are isomorphous: ellipticine-iodoCpG crystals are monoclinic, space group P2/sub 1/, with a = 13.88 A, b = 19.11 A, c = 21.42 A, ..beta.. = 105.4; TMP-iodoCpG crystals are monoclinic, space group P2/sub 1/, with a = 13.99 A, b = 19.12 A, c = 21.31 A, ..beta.. = 104.9. Both structures have been solved to atomic resolution by Patterson and Fourier methods, and refined by full matrix least squares. The asymmetric unit in the ellipticine-iodoCpG structure contains two ellipticine molecules, two iodoCpG molecules, 16 water molecules and 2 methanol molecules, a total of 140 atoms, whereas, in the tetramethyl-N-methyl phenanthrolinium-iodoCpG complex, the asymmetric unit contains two TMP molecules, two iodoCpG molecules, 17 water molecules and 2 methanol molecules, a total of 141 atoms. In both structures, the two iodoCpG molecules are hydrogen bonded together by guanine-cytosine Watson--Crick base-pairing. Adjacent base-pairs within this paired iodoCpG structure are separated by about 6.7 A; this separation results from intercalative binding by one ellipticine (of TMP) molecule and stacking by the other ellipticine (or TMP) molecule above or below the base-pairs. Base-pairs within the paired nucleotide units are related by a twist of 10 to 12/sup 0/. The stereochemistry observed in these model drug-nucleic acid intercalative complexes is almost identical to that observed in the ethidium-iodoUpA and iodoCpG complexesdetermined previously. This stereochemistry is also very similar to that observed in the 9-amino-acridine-iodoCpG and acridine orange-iodoCpG complexes.
- Research Organization:
- Univ. of Rochester, NY (United States)
- DOE Contract Number:
- EY-76-C-02-3490
- OSTI ID:
- 6299383
- Report Number(s):
- UR-3490-1595
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKALOIDS
CRYSTAL STRUCTURE
NUCLEOSIDES
PHENANTHROLINES
BOND LENGTHS
STEREOCHEMISTRY
HETEROCYCLIC COMPOUNDS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RIBOSIDES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)