Tumor-promoting phorbol esters such as phorbol 12-myristate 13-acetate (PMA) induce the monocytoid differentiation of HL-60 human leukemia cells. The cellular receptor for PMA is protein kinase C. However, cellular events distal to protein kinase C phosphorylation are also critical steps toward differentiation. These events may include specific programs of oncogene transcription that have been ...

The use of a quartz crystal microbalance (QCM) for monitorin g in situ the immobilization of singlestrand DNA marked with mercaptol group at the 5'-end on the surface of a gold-filled 7.995 MHz AT-cut quartz crystal by Au–S bond with the self-assembly technique is reported. The hybridization of ssDNA with complementary 10-mer ODN and 8-mer ODN is described. The QCM was also employed to analyze ...

The laboratory evolution of enzymes with tailor-made DNA cleavage specificities would represent new tools for manipulating genomes and may enhance our understanding of sequence-specific DNA recognition by nucleases. Below we describe the development and successful application of an efficient in vivo positive and negative selection system that applies evolutionary pressure either to favor the cl...

‘l’l~e SWYW EcoKI restriction endonuclease cleavage sites in bacteriophage P%d DNA have been mapped. The cleavage site map of circularly permut.ed P22 linear DNA is a circle. The positions of EcoRI sites in the early region of the P22 genomc were determined by comparing products of EcoRI digestion of maturtx liaear P22 chromosomes with the EcoRI cleavage fragments of DNA of three XimmP22 hybrid...

To analyse the mechanism and kinetics of DNA strand cleavages catalysed by the serine recombinase Tn3 resolvase, we made modified recombination sites with a single-strand nick in one of the two DNA strands. Resolvase acting on these sites cleaves the intact strand very rapidly, giving an abnormal half-site product which accumulates. We propose that these reactions mimic second-strand cleavage o...

Replicating DNA molecules of SV40 labeled with 13H]thymidine in the newly synthesized strands were examined by sedimentation in neutral and alkaline sucrose gradients after cleavage by the Escherichia co2i B restriction endonuclease. This nuclease creates 1 double strand break per superhelical SV40 DNA molecule. An intermediate in the cleavage of labeled replicating molecules was identified wit...

We describe the synthesis of an abasic RNA phosphoramidite carrying a photocleavable 1-(2-nitrophenyl)ethyl (NPE) group at the anomeric center and a triisopropylsilyloxymethyl (TOM) group as 2'-O-protecting group together with the analogous DNA and the 2'-OMe RNA abasic building blocks. These units were incorporated into RNA-, 2'-OMe-RNA- and DNA for the purpose of studying their chemical stabi...

A method to measure the rates of cleavage of specific sites in DNAs by restriction endonucleases is described. Partial digests are prepared by incubating DNAs with limiting amounts of endonuclease. The termini generated by cleavage are labeled with “P by the polynucleotide kmaseexchange reaction. The labeled termini are then identified by completing the digestion with the same endonuclease and ...

Using the DNA sequencing technique of Maxam and Gilbert, we show that the protein antibiotic neocarzinostatin, cleaves double-stranded phiX174 DNA restriction fragments almost exclusively at deoxythymidylic and deoxyadenylic acid residues in a reaction requiring 2-mercaptoethanol. Overall, deoxythymidylic acid residues are attacked much more frequently than are deoxyadenylic acid residues, alth...

Iron promotes DNA damage by catalyzing hydroxyl radical formation. We examined the effect of chromatin structure on DNA susceptibility to oxidant damage. Oxygen radicals generated by H2O2, ascorbate and iron-ADP (1:2 ratio of Fe2+:ADP) extensively and randomly fragmented protein-free DNA, with double-strand breaks demonstrable even at 1 microM iron. In contrast, polynucleosomes from chicken ery...