chloroquine electrophoresis

[jlramos at samba.cnb.uam.es]

Could anyone give information about agarose gel electrophoresis in the
presence of chloroquine to compare degrees of supercoiling? 
I would need specific reference(s) about the method itself and the 
related theory.
Any detailed protocol would be wellcome as well.
Many thanx

Silvia Marques

Dpt. Bioquimica vegetal
Estacion Experimental del Zaidin
CSIC
Granada (Spain)
E-mail address: JLRAMOS at SAMBA.CNB.UAM.ES