A re-evaluation of evidence attributing the difference in cleavage rates of restriction endonuclease at different sites in the substrate to differences in Km values.

The only result supporting the hypothesis that the differences in restriction endonuclease cleavage rates at various target sites are caused by differences in Km values was reported by Forsblom, Rigler, Ehrenberg, Petterson & Philipson [(1976) Nucleic Acids Res. 3, 3255-3269]. The present work shows that the kinetic analysis in that paper is based on incorrect derivation and in fact provides no support for the hypothesis mentioned.