AFFINITY RETARDATION CHROMATOGRAPHY - CHARACTERIZATION OF THE METHOD AND ITS APPLICATION - THE DESCRIPTION OF LOW-AFFINITY LAMININ SELF-INTERACTIONS

Affinity retardation chromatography (ARC), a method for the examinatio n of low-affinity interactions, is mathematically described in order t o characterize the method itself and to estimate binding coefficients of self-assembly domains of basement membrane protein laminin. Affinit y retardation was determined by comparing the elutions on a ''binding' ' and on a ''nonreacting'' column. It depends on the binding coefficie nt, the concentrations of both ligands, and the nonbinding elution pos ition. Half maximal binding of the NH2-terminal domain of laminin B1-s hort arm to the A- and/or B2-short arms was estimated to occur at 10-1 7 mu M for noncooperative and at less than or equal to 3 mu M for coop erative binding. A model of the laminin polymerization, postulating tw o levels of cooperative binding behavior, is described. (C) 1994 Acade mic Press, Inc.