MODELS FOR ENZYME-COPPER-NUCLEIC ACID INTERACTION - INTERACTION OF SOME BIOMIMETIC COPPER-COMPLEXES DERIVED FROM SALICYLALDEHYDE, GLYCINE AND ALPHA-ALANINE WITH ADENINE AND ADENOSINE
I. Somasundaram et M. Palaniandavar, MODELS FOR ENZYME-COPPER-NUCLEIC ACID INTERACTION - INTERACTION OF SOME BIOMIMETIC COPPER-COMPLEXES DERIVED FROM SALICYLALDEHYDE, GLYCINE AND ALPHA-ALANINE WITH ADENINE AND ADENOSINE, Indian journal of chemistry. Sect. A: Inorganic, physical, theoretical & analytical, 32(6), 1993, pp. 495-501
The interaction of [CuL(H2O)] (H2L=salicylideneglycine or salicylidene
-alpha-alanine) with adenine and adenosine has been investigated using
UV-VIS, IR and EPR spectral and electrochemical techniques. Adducts o
f die type [CuL(BXH2O)n] (B = adenine or adenosine, n = 0 or 1) have b
een isolated. The spectral results show that in the present copper sch
iff base complexes N(7) of adenosine and adenine are involved in bindi
ng. The enhancement in E1/2 and g(parallel-to) values for the copper c
omplexes on adduct formation with adenine and adenosine suggests the p
romotion of N(7) site with pi-bonding. The higher v(max)BAR values obs
erved for the adenine and adenosine adducts compared to those for cyto
sine and cytidine ones indicate that N(7) site of purines is preferred
to N(3) of pyrimidines. The g(parallel-to) and E1/2 values for the ad
enosine adducts are lower than those for adenine adducts, revealing th
at the electronic rather than the steric effects of CH2-ribose moiety
determine the extent of interaction of the purines. EPR and electroche
mical studies show that the extra methyl group present in the salala a
dducts leads to increased stabilisation of the hydrogen bond and hence
of Cu(II).