Mechanism of DNA cleavage catalyzed by Mung Bean Nuclease

The binding of zinc (II) to a double-stranded oligodeoxyribonucleotide. A voltammetric study

“…The reduction of adenine and cytosine residues was also verified by the appearance of the cathodic peak near À1.3 V after the addition of each ssoligo. After these experiments, we concluded that: all the three single-stranded oligodeoxyribonucleotides interact with zinc ions, by the same mechanism [41,43,44]. The size and base sequence of the oligo do not interfere in the signals of the interaction, although the smaller ones produced better results.…”

“…The interaction of zinc ions with three single-stranded oligodeoxyribonucleotides was studied by cyclic voltammetry [41,43,44] in order to determine optimal experimental parameters (DNA size, base sequence) for the synthesis of a model of double-stranded DNA (oligo). ARC5IIC2 (MM = 4472 g mol À1 ) is a single-stranded oligodeoxyribonucleotide 14 mer, whose sequence (ACACCCAACGGAGA) corresponds to part of the coding region of an arcelin gene, a protein of the lectin family, found in seeds of wild bean.…”

“…A plot of this equation yields a straight line; the slope can be used to determine the diffusion coefficient of the system. However, in the presence of the ss-oligo the electrochemical behavior of zinc changed and its oxidation-reduction process was no longer controlled by diffusion [41,43,44].…”

“…The high efficiency of the synthesis was attested by the recovery rates obtained for each step that ranged from 97% to 100% [41,44,45]. MALDI-TOF/MS experiments attested the purity of the two complementary strands of the 19 mer double-stranded oligodeoxyribonucleotide [41,44,45]. For both strands, only one peak was observed in their mass spectra, whose experimental masses (1=5869.99 Da and 2=5877.58 Da) were very similar to the theoretical values calculated for each oligo (1=5867.71 Da and 2=5876.71 Da).…”

“…Zinc amperometric titrations were performed to determine the stoichiometry, dissociation constant and zinc binding sites of a Zn 2+ -DNA complex and to understand the specific changes of ds-oligodeoxyribonucleotide secondary structure by zinc ions binding. These findings were employed to formulate a mechanism for DNA cleavage catalyzed by mung bean nuclease [40,41].…”