High affinity binding of ochratoxin A to plasma constituents.

The binding properties of ochratoxin A to human and porcine plasma constituents were studied in vitro. Ochratoxin A was shown to bind to other plasma constituents with a considerably higher affinity than the earlier known nonspecific binding to plasma albumins. The association constant for the high affinity macromolecule (s) in human plasma was found to be 2.3 X 10(10) M-1 and for porcine plasma 0.59 X 10(10) M-1. The macromolecule (s) to which ochratoxin A binds more specifically than to albumins have not been identified, but their molecular weights were estimated by gel filtration to be 20 000.