Fuente: WIPO "tomato" The present invention relates to a method for generating ssDNA guides from dsDNA using an Argonaute protein. Said guides may be useful in applications, like selectively reducing repetitive sequences in sequencing libraries using Argonaute proteins. The invention further relates to a method for cleaving a nucleic acid molecule, a method for reducing the number of nucleic acid molecules comprising a target sequence and a method for selectively enriching and/or sequencing nucleic acid molecules in a sample, like a DNA sequencing library.