A process of forming a double strand cleavage in DNA includes providing a reaction mixture containing double stranded DNA having a break in a first strand defining a target site in a second strand. The method continues by adding to the reaction mixture a photoreactive lysine conjugate selected from a lysine-enediyne conjugate, a lysine-acetylene conjugate or a combination thereof, for a time sufficient for the lysine conjugate to bind to the DNA adjacent the target site. The reaction mixture is then irradiated with electromagnetic radiation sufficient to photoactivate the lysine conjugate to cleave the second strand adjacent the target site.