Asp-Ala-His-Lys (DAHK) inhibits copper-induced oxidative DNA double strand breaks and telomere shortening

Both DNA and the telomeric sequence are susceptible to copper-mediated reactive oxygen species (ROS) damage, particularly damage attributed to hydroxyl radicals. In this study, ROS-induced DNA double strand breaks and telomere shortening were produced by exposure to copper and ascorbic acid. Asp-Ala-His-Lys (DAHK), a specific copper chelating tetrapeptide d-analog of the N-terminus of human albumin, attenuated DNA strand breaks in a dose dependent manner, d-DAHK, at a ratio of 4:1 (d-DAHK:Cu), provided complete protection of isolated DNA from double strand breaks and, at a ratio of 2:1 (d-DAHK:Cu), completely protected DNA in Raji cells exposed to copper/ ascorbate, Southern blots of DNA treated with copper/ ascorbate showed severe depletion and shortening of telomeres and Raji cell treated samples showed some conservation of telomere sequences. d-DAHK provided complete telomere length protection at a ratio of 2:1 (d-DAHK:Cu), The human albumin N-terminus analog, d-DAKK, protects DNA and telomeres against copper-mediated ROS damage and may be a useful therapeutic adjunct in ROS disease processes, (C) 2001 Academic Press.