Nucleic acid molecule having binding affinity to a target molecule and a method for generating the same

A method for generating a nucleic acid molecule that binds a target molecule comprising the following steps:

• a) providing a reference nucleic acid molecule, wherein the reference nucleic acid molecule binds the target molecule and wherein the reference nucleic acid molecule comprises a sequence of nucleotides, wherein the sequence of nucleotides comprises n nucleotides:
• b) preparing a first level derivative of the reference nucleic acid molecule, wherein the first level derivative of the reference nucleic acid molecule differs from the reference nucleic acid molecule at one nucleotide position, wherein the first level derivative is prepared by replacing the ribonucleotide at the one nucleotide position by a 2′-deoxyribonucleotide in case the reference nucleic acid has a ribonucleotide at the nucleotide position and wherein the first level derivative is prepared by replacing the 2′-deoxyribonucleotide at the one nucleotide position by a ribonucleotide in case the reference nucleic acid has a 2′-deoxyribonucleotide at the nucleotide position, and wherein the nucleotide position at which the replacement is made is the modified nucleotide position;
• and
• c) repeating step b) for each nucleotide position of the reference nucleic acid molecule, thereby preparing a group of first level derivatives of the reference nucleic acid molecule, wherein the group of first level derivatives of the reference nucleic acid molecule consists of n first level derivatives, wherein each of the first level derivatives of the reference nucleic acid molecule differs from the reference nucleic acid molecule by a single nucleotide replacement and wherein each of the first level derivatives of the reference nucleic acid molecule has a single modified nucleotide position which is different from the single modified nucleotide of all of the single modified nucleotide positions of the other first level derivatives of the group of first level derivatives of the reference nucleic acid molecule.

A nucleic acid molecule that binds a target molecule,

• wherein the nucleic acid molecule has a binding affinity to the target molecule,
• wherein the binding affinity of the nucleic acid molecule to the target molecule is increased or the same as compared to the binding affinity of a reference nucleic acid molecule to the target molecule,
• wherein
• 1) the nucleic acid molecule comprises a sequence of nucleotides and the reference nucleic acid molecule comprises a sequence of nucleotides, or
• 2) the nucleic acid molecule comprises a sequence of nucleotides and at least one modification group and the reference nucleic acid molecule comprises a sequence of nucleotides and the at least one modification group,
• wherein the sequence of nucleotides of the nucleic acid molecule and the sequence of nucleotides of the reference nucleic acid molecule are at least partially identical with respect to the nucleobase moiety of the nucleotides but differ with respect to the sugar moiety of the nucleotides,
• wherein the sequence of nucleotides of the nucleic acid molecule consists of both ribonucleotides and 2′-deoxyribonucleotides and wherein the sequence of nucleotides of the reference nucleic acid molecule consists of either ribonucleotides or 2′-deoxyribonucleotides.