RECOMBINANT HUMAN O-6-ALKYLGUANINE-DNA ALKYLTRANSFERASE INDUCES CONFORMATIONAL CHANGE IN BOUND DNA

Circular dichroism, and steady-state and time-resolved fluorescence sp ectroscopy were used to compare the native recombinant human DNA repai r protein O-6-alkylguanine-DNA alkyltransferase (AGT) with AGT bound t o ds-DNA. Contrary to fluorescence, analysis of the far-UV CD spectra indicated a conformational change of AGT upon binding to DNA: its alph a-helical content is increased by similar to 12%. Analysis of near-UV CD spectra revealed that DNA was also affected, probably being separat ed into single strands locally. (C) 1997 Federation of European Bioche mical Societies.