Diastereomeric 8,5'-cyclopurine 2'-deoxynucleosides, containing a covalent bond between the deoxyribose and the purine base, represent an important class of DNA damage induced by ionizing radiation. The 8,5'-cyclo-2'-deoxyguanosine lesion (cdG) has been recently reported to be a strong block of replication and highly mutagenic in Escherichia coli. The 8,5'-cyclopurine-2'-deoxyriboses are suspec...

We report calculations of the vibrational spectrum of HD2 in its first-excited electronic state by using a coordinate-transformation technique. The implications of the geometric phase (GP) effect in the spectrum have been investigated. The results show that the lowest 45 vibrational levels calculated using the traditional Longuet-Higgins phase (φ/2, where φ is the pseudorotation angle) are in g...

In the mol-ecule of the title compound, [FeCl(2)(C(25)H(19)N(3))], the three N atoms span the axial-equatorial-axial sites of the trigonal-bipyramidal coordination polyhedron; the geometry of the Fe(II) atom is 32% distorted from trigonal-bipyramidal (towards square-pyramidal along the Berry pseudorotation pathway). One of the Cl atoms is disordered over two positions in a 0.938 (11):0.062 (11)...

In the mol-ecule of the title compound, [MnCl(2)(C(25)H(19)N(3))], the three N atoms span the axial-equatorial-axial sites of the trigonal-bipyramidal coordination polyhedron; the geometry of the Mn(II) atom is 34% distorted from trigonal-bipyramidal (towards square-pyramidal along the Berry pseudorotation pathway). One of the Cl atoms is disordered over two positions in a 0.82 (3):0.18 (3) rat...

Conformational preferences of the pyrrolidine ring in nucleotide analogs 7-14 were investigated by means of NMR and molecular modeling. The effect of the relative configuration of hydroxy and nucleobase substituents as well as the effect of the alkylation or acylation of the pyrrolidine nitrogen atom on the conformation of the pyrrolidine ring were studied. The results of a conformational analy...

Uridine 2',3'-cyclic phosphonate (I) is slowly hydrolyzed by ribonuclease-A with k(2) and K(m) values at pH6 that are respectively 1900 and 15 times smaller than the same parameters at the same pH for the related phosphate (II). Since the ratio of rate constants for hydroxide ion catalyzed hydrolysis is about 4, this result is consistent with, but does not prove a mechanism for the enzymic reac...

Institut für Anorganische und Analytische Chemie, Freie Universität Berlin, D-1000 Berlin 33, F R G Z. Naturforsch. 43b, 245-247 (1988); received October 7/October 12, 1987 77Se NMR Spectra, Raman Spectra, Elemental Sulfur, Selenium Sulfides The 77Se NMR spectrum of l,2-Se2S5 exhibits one singlet at 1077.3 ppm indicating pseudorotation in solution; the same conclusion is reached from the soluti...