The present invention relates to a method for the production of a serine ADP-ribosylated protein or peptide comprising preparing an aqueous buffered solution comprising 5 to 60 mM, preferably 10 to 60 mM of a buffer and having a pH between 5.0 and 9.0, preferably between 5.5 to 8.5, and most preferably between 6.1 to 8.3, said solution further comprising (a) 0.2 to 2.5 mM NAD.sup.+, (b) at least 50 nM, preferably 50 to 3000 nM PARP-1, PARP-2 or the PARP-1 variant E988Q, (c) at least 100 nM, preferably 100 to 5000 nM HPF1, (d) at least 10 μg/mL, preferably 10 μg/mL to 200 μg/mL sonicated DNA, said sonicated DNA preferably comprising DNA fragments of 10 to 330 bp, and (e) up to 600 μM protein or peptide, said protein or peptide comprising at least one serine, thereby generating a reaction mix, in which the protein or peptide becomes serine ADP-ribosylated.