Biologically stable xnazyme that efficiently silences gene expression in cells

A method of treating a disease or condition or a symptom thereof, the method comprising administering an effective amount of a 10-23 analogue composition to a subject in need thereof, wherein the composition comprises:

• a) a 15-nucleotide catalytic domain according to SEQ ID NO:
• 1, wherein one or more nucleic acids of the catalytic domain is replaced by xeno-nucleic acids (XNA);
• b) a first substrate recognition domain 5′ to the catalytic domain;
• c) a second substrate recognition domain 3′ to the catalytic domain;
• and
• d) a 5′ terminal threose nucleic acid (TNA) residue;
• and
• e) a 3′ terminal TNA residue;
• wherein one or more nucleic acids of the first substrate recognition domain or the second recognition domain is replaced by XNA.

A method of validating gene mutations associated with a disease or condition, the method comprising:

• a) administering a 10-23 analogue composition to a cell line or animal model, wherein the composition comprises:
• i) a 15-nucleotide catalytic domain according to SEQ ID NO:
• 1, wherein one or more nucleic acids of the catalytic domain is replaced by xeno-nucleic acids (XNA);
• ii) a first substrate recognition domain 5′ to the catalytic domain;
• iii) a second substrate recognition domain 3′ to the catalytic domain;
• iv) a 5′ terminal threose nucleic acid (TNA) residue;
• and
• v) a 3′ terminal TNA residue;
• wherein one or more nucleic acids of the first substrate recognition domain or the second recognition domain is replaced by XNA;
• and
• b) analyzing the cell line for characteristics associated with the disease or condition.