d(GC) - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and Pharmacy
Vol. 6 (2) 204-209 April 2012, ISSN 0973-8916 (Print), 2230-7303 (Online)
upon the species present under a given set of
conditions, this prompted us to carry out to study
the Al-DNA interaction using Al maltol at neutral
pH.
Materials and Methods
Chemicals: Poly d(GC).d(GC) (Sodium salt),
poly d(AT).d(AT) (Sodium salt), Aluminum
chloride hexahydrate, Maltol, HEPES, EDTA and
EtBr were procured from Sigma chemicals. Poly
d(GC).d(GC) and poly d(AT). d(AT) was used
without further purification. Al-maltol has been
synthesized according to the method of
Finneagen et.al. (19). Purity of Al-maltol has been
checked by UV and IR spectroscopy.
Circular dichroism (CD) Studies: The Circular
dichroism spectra (190-300 nm) were recorded
for poly d(GC).d(GC) and poly d(AT).d(AT) in
the absence and presence of Al-maltol (50-
200μM ) in 1μM HEPES at pH 7.0 on a JASCO-J-
715 Spectropolarimeter at 20 o C by using 1 mm cell.
Each spectra is the average of four recordings.
Results
CD spectra: Poly d(GC).d(GC) was titrated with
Al-maltol (50-200µm ) and CD spectra were
recorded for each titration at pH.7.0 in 1mM HEPES
buffer. Normal B-DNA conservative spectrum is
observed for poly d(GC).d(GC) alone (Fig 1.a).
At 50µm level of Al maltol there is disappearance
of large positive peak at 190nm, a strong B-DNA
peak (Fig 1.b). The group of spectra (Fig 1.c,d&e)
which possesses features of left-handed Z –DNA
helix were treated with 100, 150 and 200 μM of
Al-maltol respectively. The spectra have two
negative peaks at 290nm and at 198 nm. There is
also shift in the 200nm cross-over of the B-DNA to
lower wavelength (