POLARIZED RAMAN-SPECTRUM OF SINGLE-CRYSTAL URIDYLYL (3'-5')ADENOSINE - LOCAL RAMAN TENSORS OF SOME FUNCTIONAL-GROUPS

Polarized Raman scattering measurements have been made of a single cry stal of uridylyl(3'-5')adenosine (UpA) by the use of a Raman microscop e with 488.0 nm excitation. The UpA crystal belongs to space group P2( 1) (monoclinic), and Raman intensities I-aa, I-bb, and I-c'c', have be en determined for each Raman band. These intensities correspond to the aa, bb, and c'c' components of the crystal Raman tensor; where c' is defined as an axis perpendicular to the crystallographic a axis in the ac plane. From these experimental data and by taking the known crysta l structure into account, anisotropic and isotropic molecular Raman te nsors have been calculated for the following II normal modes: ring str etching modes of the adenine residue (protonated) at 1560, 1516, 1330, and 715 cm(-1); ring str etching modes of the uracil residue at 1696, 1657, 1615, 1228, and 790 cm(-1); PO2- symmetric stretching mode at 1 080 cm(-1); P-O single bond stretching mode at 801 cm(-)1(.) These pie ces of information of the Raman tensors are considered to be useful fo r estimating the orientations of the DNA and RNA strands in a biologic al complex from a polarized Raman spectroscopic measurement of such a complex. (C) 1998 John Wiley & Sons, Inc.