electronic reprint Synchrotron radiation circular dichroism ...

obtained after irradiation of the samples for up to 3 h at one wavelength
in the UV range ( 220±230 nm). The results from the present
study seem somewhat incompatible with those observations, in that
irradiation over the entire range from 160 to 300 nm at much higher
intensities produced no such detectable changes. The samples in the
previous studies were not characterized in terms of their chemical
integrity following the procedures. The present studies, however,
have included careful characterizations of the protein by both gel
electrophoresis and mass spectrometry to demonstrate the lack of
chemical modi®cation to the protein as a result of any of the handling
or irradiation procedures.
In summary, irradiation of myoglobin at VUV wavelengths in the
SRCD appears to have resulted in no damage, crosslinking or cleavage
of the protein, despite the high intensity of the beam. Thus, it
should be possible to make SRCD measurements over a considerable
period of time without concern of altering the chemistry or structure
of the sample.
We thank Neil Freeman of GlaxoSmithKline and Dr Peter Bayley
of NIMR for helpful discussions, and the staff and scientists of station
research papers
3.1 at Daresbury and station UV1 at ASTRID for use of the facilities.
We acknowledge the BBSRC for provision of beam time at the SRS.
This work was supported by a grant from the BBSRC to BAW. AJWO
was supported by a BBSRC studentship and MH was supported by a
project grant from the Wellcome Trust to BAW.
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J. Synchrotron Rad. (2001). 8, 1027±1029 Received 5 February 2001 Accepted 12 March 2001 1029
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