1H-NMR effects in chloroquine-biopolymer binding interactions

Chloroquine (CQ), an antimalarial and anti-inflammatory drug, is known to concentrate within lysosomes. 1H-NMR studies were conducted using the resonances of CQ itself during binding interactions with various polymers and proteins including lysosome fractions isolated from rodent livers by tritosome technique. Albumin, butyrylcholinesterase, and high molecular weight DNA interact with CQ, producing marked line-width changes that correlate with effective molecular weight. Triton WR-1339 and sucrose, probable contaminants of the lysosomal materials isolated, produced essentially no effect beyond a viscosity component. Lysosomal matrix and membrane fractions exhibited relatively weak interactions, membranes being the more tenacious toward CQ. Estimated binding constants are too small to permit explanation of CQ uptake in terms of protein affinity. The evidence is more consistent with a proton-pump trapping model proposed by de Duve et al.