Binding of lysozyme to brush border membranes of rat kidney

The binding of ¹²⁵I-labelled egg-white lysozyme to isolated brush border membranes of rat kidney cortex was investigated. The lysozyme binding was reversible and saturable. The Scatchard plot revealed a one-component binding type with a dissociation constant of 7.8 μM and 15.6 nmol/mg membrane protein for the number of binding sites. The binding of the basic lysozyme could be reduced by basic amino acids such as l-lysine, l-ornithine or l-arginine, while neutral amino acids such as l-citrulline or l-alanine had no effect. The inhibitory effect of lysine was competitive.