Sequence-specific DNA-protein interactions are basic to DNA function. To better understand these interactions, we studied the effect of position on cleavage of DNA by the type II restriction enzyme (EC 3.1.21.4) Nae I. We discovered two classes of Nae I restriction sites: sites susceptible and sites resistant to cleavage. Kinetic analysis showed that Nae I was activated by DNA containing cleava...

Cleavage of pBR322 DNA I by the restriction endonuclease HinfI is preferentially inhibited at specific HinfI cleavage sites. These sites in pBR322 DNA I have been identified and ordered with respect to the frequency with which they are cleaved. The HinfI site most resistant to cleavage in pBR322 DNA I is unique in that runs of G-C base pairs are immediately adjacent on both sites. Two different...

Various antitumor drugs stabilize DNA topoisomerase II-DNA transient covalent complexes. The complexes distribution along pBR322 DNA was shown previously to depend upon the nature of the drug (Tewey et al. (1984) Science 226, 466-468). The position in pBR322 of DNA cleavage by calf DNA topoisomerase II for 115 such sites stabilized by an ellipticine derivative and the relative frequency of clea...

In this study, we further examined the sequence selectivity of camptothecin in mammalian topoisomerase I cDNA from human and Chinese hamster. In the absence of camptothecin, almost all the bases at the 3'-terminus of cleavage sites are T for calf thymus and wheat germ topoisomerase I. In addition, wheat germ topoisomerase I exhibits preference for C (or not T) at -3 and for T at -2 position. As...

The 12/23 rule is a critical step for regulation of V(D)J recombination. To date, only the RAG proteins and high mobility group protein 1 or 2 have been implicated in 12/23 regulation. Through protein fractionation and biochemical experiments, we find that Ku70/Ku80 and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) modulate RAG-mediated cleavage. Modulation of cleavage by Ku70/80 an...

Restriction endonucleases recognize short DNA sequences and cleave double-stranded DNA at specific sites within or adjacent to the recognition sequences. Restriction endonuclease cleavage of DNA into discrete fragments is one of the most basic procedures in molecular biology. The first method presented in this unit is the cleavage of a single DNA sample with a single restriction endonuclease. A...

The natural product jadomycin B, isolated from Streptomyces venezeulae ISP5230, has been found to cleave DNA in the presence of Cu(II) ions without the requirement for an external reducing agent. The efficiency of DNA cleavage was probed using supercoiled plasmid DNA in buffered solution as a model environment. EC₅₀ and t(½) values for cleavage were 1.7 μM and 0.75 h, respectively, and varied ±...

This paper is the first phytochemical and ABTS cation radical decolorisation activity, cupric reducing antioxidant capacity, anticholinesterase and DNA damage protection effect of endemic Verbascum pinetorum (Boiss.) O. Kuntze. Phenolic profile of V. pinetorum were qualified and quantified by UHPLC-ESI-MS/MS analysis. Malic acid (47250.61±2504.28 µg/g) and luteolin (7651.96±527.98 µg/g) were fo...

The cytotoxicity of several important antitumor drugs depends on formation of the covalent topoisomerase-DNA cleavage complex. However, cellular processes such as DNA replication are necessary to convert the cleavage complex into a cytotoxic lesion, but the molecular mechanism of this conversion and the precise nature of the cytotoxic lesion are unknown. Using a bacteriophage T4 model system, w...

Antineoplastic intercalating agents such as 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA) stabilize a cleavable com plex between topoisomerase II and DNA. The production of proteinassociated DNA cleavage in whole cells exposed to m-AMSA is thought to represent the cellular correlate of this topoisomerase II-mediated reaction. Protein-associated DNA cleavage can be quantified in mam ma...