Binding of the strong bacterial mutagen, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to bovine serum albumin.

Binding of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) to bovine serum albumin (BSA) was studied. MX bound mainly reversibly to BSA but, for a minor part, also irreversibly. It was possible to extract the main part of the reversibly bound MX with ethyl acetate and the extractable compound was chromatographically identical to MX. The affinity-binding characteristics of the interaction with albumin were K = 1.6 x 10(7) M-1, n = 3.4. Furthermore, mutagenicity studies indicated that reversibly bound MX remained mutagenic but that irreversibly bound MX was no longer mutagenic in the Ames test. These results suggest that the binding of MX to albumin is an important factor for both the toxicological effects and the toxicokinetics of MX.