Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Oligonucleotides of nonregular heteropyrimidine sequences incorporating or not incorporating purine residues 5'-d(ACTCCCTTCTCCTCTCTA), 5'-d(ACTCCCTGGTCCTCTCTA), 5'-d(TCTCTCCTGGTCCCTCC), and 5'-d(TCTCTCCTCTTCCCTCC) can form self-associated parallel-stranded (ps) structures at pH 4-5.5. The ps structures were identified by studying at neutral and acidic pH UV melting transitions, FTIR spectra, and fluorescence of pyrene-labeled oligonucleotides as well as by chemical joining of 5'-phosphorylated oligonucleotides. A gel electrophoresis run for oligonucleotides 5'-d(TCTCTCCTCTTCCCTCC) and 5'-d(ACTCCCTTCTCCTCTCTA) has shown the formation of homoduplexes at low DNA strand concentrations. Ps structures are held by C-C(+) base pairs and have N- and S-types of sugar puckering as detected by FTIR spectroscopy in the millimolar concentration range. Guanine inserts as well as thymine and purine inserts into an oligomeric cytosine sequence make the formation of the tetraplex i-motif unfavorable. MvaI restriction endonuclease, which recognizes the CCT/AGG sequence in DNA, does not cleave parallel pseudosubstrates.
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PMID:Parallel self-associated structures formed by T,C-rich sequences at acidic pH. 1102 45

Double-stranded cDNA has been synthesized from a polyadenylylated potato spindle tuber viroid (PSTV) template and inserted in the Pst I endonuclease site of plasmid pBR322 by using the oligo(dC).oligo(dG)-tailing procedure. Tetracycline-resistant ampicillin-sensitive transformants contained sequences complementary to PSTV [(32)P]cDNA, and one recombinant clone (pDC-29) contains a 460-base-pair insert. This cloned double-stranded PSTV cDNA contains the cleavage sites for six restriction endonucleases predicted by the published primary sequence of PSTV as well as one additional site each for Ava I, Hae III, Hpa II, and Sma I. The additional Ava I, Hpa II, and Sma I sites are explained by the presence of a second C-C-C-G-G-G sequence in the cloned double-stranded cDNA. The largest fragment released by Hae III digestion contains approximately 360 base pairs. These results suggest that we have cloned almost the entire sequence of PSTV, but the sequence cloned differs slightly from that published. Hybridization probes derived from pDC-29 insert have allowed detection and preliminary characterization of RNA molecules having the same size as PSTV but the opposite polarity. This RNA is present during PSTV replication in infected tomato cells.
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PMID:Molecular cloning and characterization of potato spindle tuber viroid cDNA sequences. 1659 77

G+C-rich satellite DNA, representing about 19% of total nuclear DNA, was isolated from various tissues of the monocotyledonous plant, Scilla siberica, by using Ag(+)-Cs(2)SO(4) gradient techniques. This satellite DNA had an unusually high melting point and a high methylcytosine (m(5)C) content ( approximately 25% of total bases; m(5)C/cytosine ratio approximately 1.5) and was localized, by in situ hybridization, in the heterochromatin regions of the chromosomes. Digestion with restriction endonuclease Hae III yielded a series of fragments ranging from 35 to several hundred nucleotide pairs. The major fragments, I-IV (35, 50, 59, and 69, nucleotide pairs, respectively), were isolated, and their nucleotide sequences were determined. The dominant fragment I was a highly symmetrical molecule, with a basically palindromic arrangement. This sequence represented the basic unit of Scilla satellite DNA and was tandemly repeated many times, with some base substitutions and multiple successive insertions of the tetranucleotide G-T-C-C. The dinucleotide CpG was the commonest nearest-neighbor sequence. Thin layer chromatography, DNA sequence analysis, and gas chromatography combined with mass spectrometry showed the high m(5)C content (m(5)C/Cyt = 2.2 and 2.8, respectively, for fragments II and III). Identical cleavage fragments were found in satellite DNAs from two other species of this genus (S. amoena and S. ingridae), which suggests that this constitutively methylated sequence is evolutionarily stable. The sequence arrangement of this plant satellite DNA is compared with those reported for several animal satellite DNAs.
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PMID:Sequence arrangement of a highly methylated satellite DNA of a plant, Scilla: A tandemly repeated inverted repeat. 1659 53


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