Imprinting of Proteins on Poly mer-Coated DNA for Affinity Separation with Enhanced Selectivity

A temperature-responsive polymer, poly(N-isopropyl acrylamide) terminated with psoralen, has been synthesized. Photo-induced reaction between DNA and psoralen end group on the polymer resulted in the grafting of poly(N-isopropyl acrylamide) on double-stranded DNA. The conjugate was found to form a precipitate at temperatures above 31°C and was easily collected by centrifugation. In this precipitation process, the conjugate collected DNA binders from solution. On the other hand, the binding efficiency of these molecules to the conjugate decreased significantly with an increasing level of DNA modification by the polymer. This blocking effect was utilized for protein imprinting on the DNA. Pre-incubation of the restriction endonuclease EcoRI with DNA results in selective preservation of its binding site from polymer modification. Bioimprinting is a potentially facile method for the preparation of selective collectors for site-specific DNA binders.