%A A Ozdemir
%A IK Lednev
%A SA Asher
%J Biochemistry
%T Comparison between UV Raman and circular dichroism detection of short ? helices in bombolitin III
%X We have used UV resonance Raman (UVRR) and circular dichroism (CD) spectroscopies to examine the dilute solution-phase secondary structure of the 17 amino acid peptide Bombolitin III (BIII). Both UVRR and CD clearly observe the ?-helix structure induced by the addition of trifluoroethanol (TFE) to BIII. In contrast, only UVRR is able to detect the single ?-helical turn induced by increasing the pH of BIII from pH 1.8 to 6.4. This ?-helical turn is formed because of a stabilizing salt bridge formed between Lys2 and Asp5. Further increases in the ?-helix content occur as the pH is raised further. We compare the relative sensitivity of UVRR and CD to short ? helices and find, as expected, that the CD cannot detect short ? helices. This study demonstrates that UV Raman measurements can detect the formation of single ?-helical turns which cannot be detected by CD measurements.
%N 6
%P 1893 - 1896
%V 41
%D 2002
%R 10.1021/bi010970e
%L pittir17797