In spite of the fact that these two molecules be a three positively charged amino groups, ruthenium hexamine appears to be 3. 5 ti me s mo re efficient a sinhib it or of the ribozyme than coba lt hexamine. This result shows not only that the inhibition of CChMVdHHR self-cleav age is due to the positi vely-charg ed amino groups but
also that it is met a l- co re depe n den t, sugg es ti n g th at th e ru the n iu m
hexamine either can bind to an additional site(s) unreachable by the
cobalt hexamine or binds to the same site(s) with a higher affi nity. It
is in te re s ti ng t o re la te th is ob s er va ti on wi th th at of a st ud y of th e
infl ue n c e of th e in n er co or di n a ti on sp he re of c ob a lt a nd ru the ni u m
h ex a mi n e on the ir in t er ac ti on wi th th ym us DNA in so lu ti on . Th is
st ud y sh ow ed th at th e h yd ro dy n a mi c ra di u s of ru th en iu m is muc h
la rg er th an th a t of c ob a lt [ Rh ( Co 3) = 6 5 ± 5 nm a n d Rh ( Ru 3 ) =
440 ± 30 nm] although the two compounds exert an identical global
infl uence on the structure of the macromolecule [30].