Zip nucleic acids (ZNAs) are oligonucleotides conjugated with a cationic spermine tail that increases the affinity of the oligonucleotide for its target by decreasing the electrostatic repulsions between the negative anionic charges of the ssDNA improving its hybridization, increasing and accelerating the recognition of the target . The ability to modulate the global charge of conjugated ZNAs based on the number of spermines connected to the nucleic acid oligomer is the key to easily predicting the Melting Temperature (Tm) of ZNA-DNA / ZNA-RNA hybrids. The Tm increases linearly with the length of the oligonucleotide. They are a good alternative for Minor Groove Binder (MGB) and LockedNucleic Acid (LNA).
What are they for:
... so they can be used in:
A very low Tm for oligonucleotides or very short probes is a problem that can be circumvented by adding to these oligos non-specific sub-units (as in the ZNA) that increase the Tm without losing specificity and overcoming restrictions due to very specific sequences. p>
The increase in Tm is naturally higher on oligos or shorter probes, which is why Bio-Fab has extended the length range starting from 8mers for oligos and 10mers for Dual-labeled probes.
The Tm of the ZNAs can be roughly calculated using this formula:
Tm (ZNA) = Tm (DNA) + 36z/(N-3.2)
z: number of cationic units
N: number of nucleotides
ATATATAT 8mer Tm sequence (DNA) = 16°C
ZNA-2 building block
Tm(ZNA) = 16 + 36*2/(8-3.2) = 31°C
Bio-Fab synthesizes ZNA by adding 2 or 3 “building blocks” (ZNA-2, ZNA-3) both to the primers (length between 8 and 15mers) and to the dual-labeled probes (from 10 to 17mers). ZNA-4 and ZNA-5 can be added to 16mers (ZNA-4) and 20mers (ZNA-5) primers: while for dual-labeled probes the minimum length is 18mers (ZNA-4) and 22mers ( ZNA-5).
The maximum length of the ZNA, according to our experience, is 40mers with 5 building blocks. Further modifications of the primers or probes, without changing their specificity, concern the incorporation of analogues of bases such as:
C-5-propinil dC (PDC) which raises the Tm by ~ 2.8 ° C by substitution
and / or
C-5 propinil-Du (PDU) which raises the Tm by ~ 1.7 ° C by substitution.
Please note: ZNA blocks can only be added to the 3'or 5 '.
All oligo ZNA will be delivered dissolved in H2O (pH 7-9) at the concentration of 100 µM
To order ZNA (specify the type of delivery / collection directly in the email)
DOWNLOAD FORM ZNA SUMMARY