The Pseudomonas bacteriophage Pf1 is a long ( approximately 2000 nm) and thin ( approximately 6.5 nm) filament consisting of a covalently closed, single-stranded DNA genome of 7349 nucleotides coated by 7350 copies of a 46-residue alpha-helical subunit. The coat subunits are arranged as a superhelix of C(1)()S(5.4)() symmetry (class II). Polarized Raman and polarized FTIR spectroscopy of oriented Pf1 fibers show that the packaged single-stranded DNA genome is ordered specifically with respect to the capsid superhelix. Bases are nonrandomly arranged along the capsid interior, deoxynucleosides are uniformly in the C2'-endo/anti conformation, and the average DNA phosphodioxy group (PO(2)(-)) is oriented so that the line connecting the oxygen atoms (O.O) forms an angle of 71 degrees +/- 5 degrees with the virion axis. Raman and infrared amide band polarizations show that the subunit alpha-helix axis is inclined at an average angle of 16 degrees +/- 4 degrees with respect to the virion axis. The alpha-helical symmetry of the capsid subunit is remarkably rigorous, resulting in splitting of Raman-active helix vibrational modes at 351, 445 and 1026 cm(-)(1) into apparent A-type and E(2)()-type symmetry pairs. The subunit tyrosines (Tyr 25 and Tyr 40) are oriented with phenoxyl rings packed relatively close to parallel to the virion axis. The Tyr 25 and Tyr 40 orientations of Pf1 are surprisingly close to those observed for Tyr 21 and Tyr 24 of the Ff virion (C(5)()S(2)() symmetry, class I), suggesting a preferred tyrosyl side chain conformation in packed alpha-helical subunits, irrespective of capsid symmetry. The polarized Raman spectra also provide information on the orientations of subunit alanine, valine, leucine and isoleucine side chains of the Pf1 virion.

The amide I Raman tensor corresponding to the antiparallel b-sheet structure in proteins has been determined by polarized Raman microspectroscopy of fowl feather rachis using polarized Raman spectra excited in the near-infrared (785 nm). For a Raman tensor principal axis system (XYZ), in which X is perpendicular to the plane of the pleated b-sheet, Y is in the plane of the sheet and perpendicular to the direction of the polypeptide chain, and Z is parallel to the direction of the polypeptide chain, the principal tensor components (a XX , a YY , a ZZ ) are found to satisfy the following relationships: R 1 ≡ a XX /a ZZ = 0.32 and R 2 ≡ a YY /a ZZ = 3.48. With this Raman tensor determination, we show that semiquantitative estimates of the total antiparallel b-sheet content in b-rich proteins can be extracted from polarized Raman intensity measurements on the amide I marker of the b-sheet occurring near 1664 cm −1 . We demonstrate this approach for the b-rich silk proteins of the silkworm and spider. INTRODUCTIONThe antiparallel chain, pleated-sheet conformation (ˇ-sheet) is a fundamental structural component of native proteins. 1 The silk of both silkworms and spiders and the rachis keratins of fowl feather barbs are examples of native proteins in which the antiparallelˇ-sheet is the major structural element. 2 A key property of theˇ-sheet structure in both silk and feathers is a high degree of polypeptide chain orientation. Thě -sheet conformation is also prevalent in nonnative and misfolded proteins and has been implicated in polypeptide † Presented as part of a commemorative issue for Wolfgang Kiefer on the occasion of his 65th birthday.

Raman spectra of single cells of Euglena and Chlamydomonas have been examined with 514.5 nm excitation at various points within the cells. At every point, two strong bands, which are assignable to carotenoid, appeared at 1530 and 1159 cm−1. By the use of a Raman mapping system, the Raman intensity at 1530 cm−1 has been plotted against the (x,y) coordinate representing a location within the cell. It has been shown that, for both algae examined, the eyespot has a prominently high carotenoid content, and a small amount of carotenoid is uniformly distributed among the chloroplast. The spatial resolution of the mapping system has been shown to be higher than 1 μm, and the Chlamydomonas eyespot has an elongated shape of 1 μm × 2 μm. By use of a polarizer, the carotenoid chains in the Chlamydomonas eyespot have been found to be aligned along its long axis, which is parallel to the body axis.

Raman spectra of undeuterated and deuterated rachis from a fowl feather was observed with 488 nm excitation in the 400–1800 cm−1 region. Fowl feather rachis and barbs were subjected to a polarized Raman microscopic examination with excitation at 785 nm. From the observed frequencies, intensities, and scattering anisotropies of the 20 Raman bands, and on the basis of known Raman tensors of the 10 localized molecular vibrations, conformations, and orientations of the polypeptide main chains, tyrosine, phenylalanine, tryptophan residues, and disulfide linkages of the protein molecules in the feather were elucidated.

The alkoxo-bridged binuclear copper(II) complexes with N,N-dialkyl-N′-(hydroxyalkyl)alkanediamine were investigated by electrochemical methods. The binuclear complexes exhibited two non-separable sequential, oneelectron steps, the half-wave potentials of which were almost identical, in N,N-dimethylformamide. On the other hand, the complexes gave two distinctive one-electron reduction waves in acetonitrile.