Telomeric DNA can fold into four-stranded structures known as G-quadruplexes. Here we investigate the ability of G-quadruplex DNA to serve as a substrate for recombinant Tetrahymena and native Euplotes telomerase. Inter- and intramolecular G-quadruplexes were gel-purified and their stability examined using native gel electrophoresis, circular dichroism (CD) and thermal denaturation. While inter...

As a consequence of being diploid, retroviruses have a high recombination rate. Naturally occurring retroviruses contain two repeat sequences (R regions) flanking either end of their RNA genomes, and recombination between these two R regions occurs at a high rate. We deduced that recombination may occur between two sequences within the same RNA molecule (intramolecular) as well as between seque...

The palladium-catalyzed intramolecular coupling of allyl stannanes with allyl carboxylates provides a general synthesis of five- and six-membered-ring carbocycles. The intramolecular coupling leads selectively to trans five-membered carbocycles and cis six-membered carbocycles, regardless of the cis or trans configuration of the allylic functions in the starting material. For example, the stere...

We report the experimental determination of the intramolecular enol-enol tautomerization rate of an unsymmetric β-diketone, benzoylacetone, with femtosecond transient absorption in the ultraviolet. Initially, there is an equilibrium of two possible enolic structures in solution, which is disturbed upon UV excitation by exciting a disproportionate fraction of one enolic form. Comparison to symme...

Intramolecular C±H insertion by Rh-mediated carbenoids has attracted considerable interest in recent years. In addition to its synthetic applications, there have been extensive investigations into the mechanism of this reaction. We have recently studied the electronic e€ects of this reaction through the measurement of the relative reactivities of Rh-mediated carbenoid insertion into a series of...

1. Applicability of the previously postulated active transport system for conveying glucose into the human red cell was tested in connection with a number of related substances, comprising 6-carbon aldoses and ketoses, 5-carbon aldoses, and 5- or 6-carbon polyhydric alcohols. 2. The alcohols did not perceptibly penetrate the cells; all the sugars penetrated, the rates differing, but all of the ...