RT Journal Article SR Electronic(1) A1 Blanch, Ewan W. A1 Robinson, David J. A1 Hecht, Lutz A1 Barron, Laurence D.YR 2001 T1 A comparison of the solution structures of tobacco rattle and tobacco mosaic viruses from Raman optical activity JF Journal of General Virology, VO 82 IS 6 SP 1499 OP 1502 DO https://doi.org/10.1099/0022-1317-82-6-1499 PB Microbiology Society, SN 1465-2099, AB Vibrational Raman optical activity (ROA) spectra of tobacco rattle virus (TRV) and tobacco mosaic virus (TMV) were measured and compared with a view to obtaining new information about the coat protein subunit structure of TRV. A sharp strong positive band observed at ∼1344 cm−1 in the ROA spectra of the two viruses is evidence that both contain a significant amount of a hydrated form of α-helix, but more in TRV than in TMV. Although the ROA spectrum of TMV shows significant positive intensity in the range ∼1297–1312 cm−1 characteristic of α-helix in a hydrophobic environment, as expected from the helix interface residues in the four-helix bundles that constitute the basic motif of the TMV coat protein fold, that of TRV shows little positive ROA intensity here. Instead TRV shows a strong positive ROA band at ∼1315 cm−1, of much greater intensity than bands shown here by TMV, that is characteristic of polyproline II (PPII) helix. This suggests that the additional long central and C-terminal sequences of the TRV coat proteins contain a significant amount of PPII structure, plus perhaps some β-strand judging by a prominent sharp negative ROA band shown by TRV at ∼1236 cm−1, but little α-helix. The open flexible hydrated nature of PPII helical structure is consistent with the earlier suggestions that the additional sequences are exposed and, together with a larger amount of hydrated α-helix, could serve to fill the extra volume required by the larger diameter of the cylindrical TRV particles relative to those of TMV., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-82-6-1499