No abstract

dApT, a modified deoxyribose dinucleoside phosphate with an uncharged methylphosphonate group, crystallizes as dihydrate in space group P2(1)2(1)2, a = 9.629(3), b = 20.884(6) and c = 14.173(4)A, Z = 4. The structure has been determined using 2176 X-ray diffractometer reflections and refined to a final R of 0.105. Torsion angles about P-O(5') and P-O(3') bonds are -91.8 degrees and 117.8 degrees. The former is in the normal (-)gauche range while the latter is eclipsed. Bases are oriented anti, the sugar of adenosine is puckered 2T3 (C(2')endo) whereas that of thymidine displays puckering disorder with major and minor occupancy sites. Major site is a half-chair 2T (C(2')endo-C(1')exo) and minor site an envelope 3T2 (C(3(1)endo). Adenine and thymine bases of symmetry related molecules form reversed Hoogsteen type base pairs, water molecules are disordered in the crystal lattice.

No abstract

2-Aminoadamantane-2-carboxylic acid hydrobromide crystallizes in space group P21/c with a= 6.40, b= 11"62 and c= 15.38 ,~, fl= 95.2 °, Z=4. The structure was solved by the heavy-atom method with 1484 visual reflexions and refined to an R of 0.097. The substitution of the amino and the carboxyl group at C(2) of the adamantane does not significantly affect its highly symmetric cage-hke structure.In relation to amino acid structures, a rare occurrence of the C(11)-O(2) double bond trans to the nitrogen N about the C(2)-C(11) bond is observed in this structure. The nitrogen atom lies 1.07 A oat of the plane containing the carboxyl group and C(2).

No abstract