Nick translation of lambda phage DNA with a deoxycytidine analog spin labeled in the 5 position

Affinity modification of human immunodeficiency virus reverse transcriptase and DNA template by photoreactive dCTP analogs

New base-substituted analogs of dCTP containing an azido group have been synthesized and applied to a selective photoaffinity modification of HIV-RT (p66/p51 heterodimer). The labeling of only the 66 kDa subunit of HIV-RT was detected when the enzyme was first irradiated with the analogs and then template (5'-(d)GGTTAAATAAAATAGTAAGAATGTATAGCCCCTACCA-3') and 5' 32P end-labeled 3'-(d)TTACATATCGGGGATGGT-5' primer were added. The 5' 32P end-labeled primer elongated by dCTP analogs in the presence of both HIV-RT and DNA template is able to modify both subunits of HIV-RT and DNA template. This way of specific cross-linking to both DNA (RNA) template and HIV-RT opens up new possibilities to study the HIV-RT active site.

An electron paramagnetic resonance probe to detect local Z-DNA conformations

We present spectroscopic evidence for an electron paramagnetic resonance (EPR) probe to detect local Z-DNA conformations in synthetic DNA. A spin labeled deoxycytidine-5'-triphosphate (pppDCAT) was co-polymerized with Micrococcus luteus DNA polymerase to yield the spin active alternating co-polymer (dG-dC,DCAT)n. The EPR spectrum of (dG-dC,DCAT)n in the Z-DNA conformation indicates a decrease in the local base dynamics by about a factor of two as compared to that computed for B-DNA. A control experiment conducted with (dA-dT, DUAT)n under similar salt conditions rules out the possibility of observing salt induced artifacts.