WHBATSTONE PHYSICS LABORATORY

SgsoU3.c Opt5oal Rotation of Nuc1el.a Acid

Om well-knormn t e of optical rotation (e. .

quartz) arises from a he1 9 owl arrangement of atoms (In
the cPyrsta2. I suppose it Is teohnically too difficult
to observe this in nucleic acid fibre8, although It
should be quite feasible in sheets. In fact it has
already been observed in gelatin films by Robinson and
Dott (Nature, 168, 325, 1951), An interesting polnt ia
that speoif3.c %%itton in mny substances is very high
near an absorption bard. Thus the optlcal rQt5an of
a fllrn of nucleh acid could be observed photographic-
ally (this is a standax4 technique) near A2500 wbra
the nucleotides absorb and the effect of nolsttwe
content and stress could also be studied. (The law
is very aidlap to that af the, Sellmsier dispersion
f ormula] o

The method has possibilitliea in solution as a

mean8 of correlation with light-scattering work. 1
doubt if it is theoretically possfble to correlate the
rotation with helical struat?a?e only since it can arise
from aspmetric carbon atomt but It might be a very
useful method in ahowing chanps of configuratbn
~qrls%ng from changes of pEI etc.