Neomycin sulfate

Neomycin interacts preferentially with the ribozyme-substrate complex and that this interaction leads to a reduction in the cleavage rate by stabilizing the ground state of the complex and destabilizing the transition state of the cleavage step. ^[1] Neomycin effects a conformational change in the structure of trans-activating region (TAR) that can be detected by circular dichroism spectroscopy. Neomycin acts as a noncompetitive inhibitor that can bind to the Tat-TAR complex and increase the rate constant (koff) for dissociation of the peptide from the RNA. ^[2] Neomycin is the most effective aminoglycoside (groove binder) in stabilizing a DNA triple helix. Neomycin stabilizes TAT, as well as mixed base DNA triplexes, better than known DNA minor groove binders (which usually destabilize the triplex) and polyamines. Neomycin shows a preference for stabilization of TAT triplets but can also accommodate CGC(+) triplets. ^[3] Neomycin induces a concentration- and voltage-dependent partial block from both the cytosolic and luminal faces of the channel. Neomycin has a greater affinity for the luminal site of interaction than the cytosolic site: zero-voltage dissociation constants (Kb(0)) are respectively 210.20 nM and 589.70 nM for luminal and cytosolic block. Neomycin also exhibits voltage-dependent relief of block at holding potentials >+60 mV. ^[4]