Tetrahydropyrimidine derivatives inhibit binding of a Tat-like, arginine-containing peptide, to HIV TAR RNA in vitro

AbstractThe ability of a small molecule, 2-methyl,4-carboxy,5-hydroxy-3,4,5,6-tetrahydropyrimidine (THP(A)), which accumulates intracellularly in various streptomyces, to inhibit the interaction of Tat peptide (R52) with TAR RNA is presented. Using gel-shift assay, we found that the inhibition constant Ki of THP(A) is 50–100 nM, which is in the range of the binding constants of Tat peptide and protein. THP(A) is ∼ 106 times more tightly bound than the free l-arginine. The high binding affinity may be attributed to the special delocalized positive charge on the NCN group and the hydroxyl group at the 5 position of this molecule. A model for THP(A)-TAR interaction, analogous to the arginine guanidinum group-TAR interaction, is presented. The relatively high uptake of THP(A) by mammalian cells warrants in vivo Tat/TAR inhibition studies

Structure–activity relationships of aminoglycoside-arginine conjugates that bind HIV-1 RNAs as determined by fluorescence and NMR spectroscopy

AbstractWe present here a new set of aminoglycoside-arginine conjugates (AACs) that are either site-specific or per-arginine conjugates of paromomycin, neamine, and neomycin B as well as their structure–activity relationships. Their binding constants (KD) for TAR and RRE RNAs, measured by fluorescence anisotropy, revealed dependence on the number and location of arginines in the different aminoglycoside conjugates. The binding affinity of the per-arginine aminoglycosides to TAR is higher than to RRE, and hexa-arginine neomycin B is the most potent binder (KD=5 and 23 nM, respectively). The 2D TOCSY NMR spectrum of the TAR monoarginine-neomycin complex reveals binding at the bulge region of TAR

Alanine - valine dynamics in pregnant rabbits

[ 15N]-alanine and [ 15N]–valine dynamics were studied in 29 -30 days pregnant New-Zealand rabbits. Over the experimental period, there was no detectable significant difference of mean ± SD of alanine concentrations within the sampling intervals in maternal, umbilical venous and arterial blood samples suggesting that alanine concentration was in a steady state and that the system was not being perturbed. Similar results were obtained for valine. The enrichment of alanine in the umbilical venous blood was 68.9 ± 2.4% lower than that simultaneously obtained from the maternal vein (P < 0.05). A decrease of 42.7 ± 4.7% in the umbilical arterial sample was observed compared to umbilical venous blood. The data suggest possible fetus production of alanine in utero. Both the maternal and foetal compartment were in isotopic steady state. Comparison of the enrichment of valine in the umbilical venous blood was 54.8 ± 6.3% less than that of the maternal blood. Statistical comparison of the umbilical venous and arterial showed no significant difference. This suggests that there was no apparent valine production during the experimental period

Alanine - valine dynamics in pregnant rabbits

[ 15N]-alanine and [ 15N]–valine dynamics were studied in 29 -30 days pregnant New-Zealand rabbits. Over the experimental period, there was no detectable significant difference of mean ± SD of alanine concentrations within the sampling intervals in maternal, umbilical venous and arterial blood samples suggesting that alanine concentration was in a steady state and that the system was not being perturbed. Similar results were obtained for valine. The enrichment of alanine in the umbilical venous blood was 68.9 ± 2.4% lower than that simultaneously obtained from the maternal vein (P < 0.05). A decrease of 42.7 ± 4.7% in the umbilical arterial sample was observed compared to umbilical venous blood. The data suggest possible fetus production of alanine in utero. Both the maternal and foetal compartment were in isotopic steady state. Comparison of the enrichment of valine in the umbilical venous blood was 54.8 ± 6.3% less than that of the maternal blood. Statistical comparison of the umbilical venous and arterial showed no significant difference. This suggests that there was no apparent valine production during the experimental period