J.H. Perrin

An unbiased method for estimating binding parameters in a non-cooperative binding process

Abstract A statistically unbiased method of estimating ligand-macromolecule binding constants from experimental data is given, assuming a non-cooperative binding process. The new method is, by application to dicumarol-albumin data, shown to give results which in some cases differ substantially from those of methods commonly used. These differences arise because the assumptions on which the commonly used methods are based are severely violated due to the experimental setup. In addition to the advantage of giving unbiased parameter estimates, the new method provides confidence intervals of the estimates and also allows for the inclusion of weights compensating for varying precision in the data.

Some quantitative investigations of the binding to and the displacement of bishydroxycoumarin from human serum albumin

Abstract The binding of dicumarol to human serum albumin fraction V has been investigated at lower drug-to-albumin ratios than in previous investigations by a circular dichroic technique. Two sites having binding constants of 2.9 × 10 6 M −1 and 1.9 × 10 5 M −1 were capable of inducing optical activity into the dicumarol. A wide range of acidic drugs was found to compete with dicumarol for these binding sites. The binding constant for chlorphenoxy-2-methylpropionate (from clofibrate) at the primary binding site of dicumarol and of warfarin was calculated from the displacement data.

Induced optical activity following the binding of warfarin, indomethacin, 4-hydroxycoumarin and salicylic acid to human serum albumin

Abstract Warfarin, 4-hydroxycoumarin, indomethacin and salicylic acid have previously been reported to show no induced optical activity on binding to human serum albumin (HSA). The binding of these drugs to HSA has been reinvestigated at higher protein concentrations by circular dichroism (CD) and all give induced Cotton effects, which in the case of the weaker acids, warfarin, 4-hydroxycoumarin and indomethacin, show considerable pH dependency.

Displacement of sulfaethidole from bovine serum albumin by some alkyldimethylbenzylammonium chlorides

Abstract Alkyldimethylbenzylammonium chlorides have been shown to displace sulfaethidole, a strongly bound sulfonamide, from bovine serum albumin, using measurements of the optical activity induced into the drug after the binding reaction. The higher homologues modify the circular dichroism spectrum of the albumin in the region associated with tryptophan and tyrosine residues. Measurements at lower wavelengths suggest that the higher homologues may cause small conformational changes in the protein.