| Abstract: | The first Raman spectra of HIV1-HIV2 in human sera and hypericin-induced photosensitive damage of the virus have been obtained.
The prominent Raman lines in the spectra are assigned respectively to the carbohydrates of viral glycoprotein, RNA, protein
and lipid. The spectra are dominated by Raman scattering of the carbohydrates. The lines of D-Mannose and N-acetylglucosamine
in carbohydrates are obvious and there is a β-configuration in the anomeric C1 position in D-Mannose. The viral RNA duplexes
bound assumes an A-form geometry. The lines of backbone phosphate group, bases (involving interbase hydrogen bonding) and
ribose of the RNA are complete and distinct. The secondary structure of the viral protein maintains α-helix, β-sheet, β-turn
and random coil. Its side chains are rich and vary from tryptophan, phenylalanine and “buried” tyrosine; the stable conformation
of the S-S bond of gauche-gauche-gauche; the two forms of C-S bonds of gauche and trans; to sulfhydrl group and ionized and
unionized carboxyl groups. The viral lipid bilayer molecules are probably in the liquid ordered phase or the gel phase. It
was observed that the hypericin-induced photosensitive damage of HIV1-HIV2 in human sera changed various components of HIV1-HIV2
in different degrees: The orderly A-form viral RNA would become a disordered viral RNA. There were a breakage of interbase
hydrogen bonds and disruption of vertical base-base stacking interactions. In addition, the groups of ribos and four bases
were damaged obviously. A decrease in ordered structure (α-helix and β-sheet) of viral protein is accompanied by an increase
in random coil. The Tyr buried in the three-dimensional structure of protein was damaged, but it was still “buried” and the
damage of C-S bond of trans form was stronger. The groups of carbohydrates, including D-Mannos and N-acetyl glucosamine, in
viral envelope glycoprotein had also been changed. The hydrophilic C-N bond of choline in viral lipid was damaged, which was
the possible binding site to hypericin, whereas the viral lipids bilayers were still probably in the liquid ordered phase
or the gel phase. So the space structure of HIV1-HIV2 was damaged under the experimental conditions, which might block viral
infection and inhibit its growth and breeding. It is apparent that the laser Raman spectra have provided certain direct evidence
at the molecular level for photosensitive damage of HIV1-HIV2. |
