DNA damage in a solution containing copper(II) ions and ascorbic acid: Effect of the presence of sulfite

Some antioxidant compounds have a pro-oxidant effect in the presence of transition metal ions, due to the reduction of Mn+ to M(n-1)+ with simultaneous formation of free radicals, which then promote DNA damage. In the present study, we evaluated the pUC19 DNA damage in a solution containing Cu(II) and ascorbic acid (AA) or S(IV) saturated with air by agarose gel electrophoresis. Our results showed that this damage decreases if AA and S(IV) are simultaneously added. This study also illustrates the importance of Cu(II) in this process, as no DNA damage was observed when AA or S(IV) were present in the absence of this metallic ion. Our data showed that DNA preservation depends on the concentration of AA and S(IV) and occurs when the [S(IV)]:[AA] ratio ranges from 1:1 to 20:1. Absorbance measurements and thermodynamic data show that no reaction occurs between AA and S(IV) when this mixture (pH 5.5) is added to pUC-19 DNA. The presence of dissolved oxygen may be the cause of AA consumption in the mixture of these two antioxidants, which subsequently decreases DNA damage.

Electroforesis de aminoácidos a alto y bajo voltaje en agarosa / Electrophoresis of aminoacid in agarose at high and low voltage

Se ha desarrollado una nueva técnica para la separación electroforética de una solución de aminoácidos, compuesta por: taurina, ácido glutámico, serina, glicina, histidina, lisina y ß-alanina; que utiliza agarosa C como medio soporte y buffer fórmico-acético (pH=2,2). Las separaciones se realizan en bajo y alto voltaje (100-150 V y 350-800 V, respectivamente) obteniéndose en este último caso una mejor resolución, el tiempo empleado varía de acuerdo con las condiciones esperimentales y no supera los treinta minutos. El método proporciona información equivalente a la obtenida por la electroforesis tradicional, en papel a alto voltaje, con un menor costo, instrumental sencillo y, además, permite la densitometría directa de las separaciones coloreadas con nihidrina; se lo aplica a la separación de aminoácidos urinarios