MGB in comparison to ZNA®-conjugated, LNA-modified oligonucleotides
MGB (Minor Groove Binder), ZNA® and LNA (Locked Nucleic Acids) are known to increase the Tm of an oligo sequence.
MGB probes include a minor groove binder moiety at the 3’ end that increases the melting temperature (Tm) of the probe and stabilizes the hybridization of the probe DNA to its target sequence. The introduction of the minor groove binder moiety is sequence-independent, meaning the core sequence remains “unmodified”.
ZNA®s are oligonucleotides conjugated with repeated cationic spermine units that decrease electrostatic repulsions with target nucleic acid strands, and greatly improve hybridization properties by enhanced affinity to the complementary target sequence as well as increased stability of the formed duplex at an unprecedented specificity. The “Tm boost” generated by adding ZNA® to either end of the oligonucleotide probe is significant and also sequence-independent.
In contrast LNA probes rely on modified nucleotide chemistry with regard to the sugar component involved, while the organic base component is “unmodified” and thus follows Watson-Crick base-pairing rules when mixed with DNA or RNA bases in an oligonucleotide. When incorporated into an oligonucleotide probe, locked nucleic acid monomers increase structural stability, resulting in a raise of the formed duplex´melting temperature (Tm). Locked Nucleic acids are not recognized by DNA/RNAses as a substrate, hence LNA modified oligonucleotides also display significant resistance to nucleases.
In summary, metabion offers all three duplex stability enhancing modifications, and therefore provides greatest flexibility in assay design and choosing the right option for your required application.