Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ability of a stretch of alternating dA-dT to adopt the left-handed Z form has been assessed by examining the behavior of the sequence d(CG)6(TA)4(CG)6 contained in the plasmid pBR322. The structural transition occurring within this sequence as a function of negative superhelicity was analyzed by several methods, including (1) the supercoiling-dependent unwinding of the insert as determined by two-dimensional gel electrophoresis, (2) the binding of anti-Z-DNA antibodies to the insert, (3) the sensitivity of the sequence to a single strand specific endonuclease, and (4) the sensitivity of the insert to digestion by a restriction endonuclease that cuts within the d(CG)6 segments when in the right-handed form. These studies have shown that in negatively supercoiled DNA the two d(CG)6 portions of the insert adopt the Z form, while the central d(TA)4 segment forms an underwound structure with a helical repeat that is best approximated as being intermediate between the B form and the Z form. A statistical mechanical treatment of the unwinding of the insert as a function of negative superhelicity provides an estimate of the minimum free energy required to convert an A-T bp from the B form to the Z form, as well as the free energy associated with the conversion of an A-T bp from the B form to the unwound form. These results strongly indicate that Z DNA is an unfavored structural alternative for stretches of d(AT)n in negatively supercoiled DNA.
...
PMID:An assessment of the Z-DNA forming potential of alternating dA-dT stretches in supercoiled plasmids. 371 51

The previously described hybrid plasmid pC7 which carries lacI+O+delta(Z)Y+A+ on a 12.3 X 10(6)-Mr DNA fragment [Teather et al. (1978) Mol. Gen. Genet. 159, 239-248] was partially digested with the restriction endonuclease EcoRI under conditions reducing the recognition sequence to d(A-A-T-T) and ligated to the vector pB322. lac Y-carrying inserts of various sized (Mr 1.5-4.7 X 10(6)) were obtained. Hybrid plasmid pTE18 (2300-base-pair insert) carries part of the I (repressor) gene, the promotor-operator region, part of the Z (beta-galactosidase) gene, the Y (lactose carrier) gene and part of the A (transacetylase) gene. Upon induction of pTE18-harbouring strains the Y-gene product is expressed at a nearly constant rate for several generations and accumulates to a level of 12-16% of the total cytoplasmic membrane protein. Integration into the membrane leads to active carrier as judged by binding and transport measurements.
...
PMID:Lactose carrier protein of Escherichia coli. Structure and expression of plasmids carrying the Y gene of the lac operon. 625 Aug 28

We have carried out studies on type II restriction endonuclease EcoRI, which cleaves the DNA sequence 5'd(-G-A-A-T-T-C-)3', as indicated. The active form of the enzyme consists of two subunits, each 31063 molecular weight. A water-soluble reagent, 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-sulphonate, which reacts with carboxyl groups and also with tyrosine and cysteine residues, has been found to inactivate this enzyme. Results are presented which show the following. (1) This specific inactivation is not due to modification of tyrosine or cysteine residues. (2) There is one carboxyl group per subunit which, when modified with carbodiimide, inactivates the enzyme. (3) phi X174 DNA (which does not contain EcoRI sites) partially protects the enzyme from the carbodiimide; protection is unaffected by the additional presence of Mg2+, but significantly greater with Co2+ and phi X174 DNA.
...
PMID:The essential carboxyl group in restriction endonuclease EcoRI. 627 65

From Caryophanon latum L site specific restriction endonuclease (ClaI) has been purified, which recognises tha DNA hexanucleotide palindrome 5'-A-T-C-G-A-T-3'. Staggered cleavage generates DNA restriction fragments with 5'-terminal pCG extensions. A CLaI map of bacteriophage lambda has been determined, which indicates cleavage inhibition due to adenine methylation at over lapping ClaI-GATC recognition sequences. Plasmid pBR322 is cut only once, in the tetracycline promoter region, and can, therefore, be used as a vector system for cloning fragments derived from ClaI digestions, and in addition for fragments generated by TaqI, HpaII, and several other enzymes.
...
PMID:ClaI. a new restriction endonuclease from Caryophanon latum L. 627 88

The cleavage of radioactively labelled double-stranded d(G-G-A-A-T-T-C-C) was studied in single turnover experiments with substrate and enzyme both being in the micromolar range. The reaction rate was found to increase with enzyme concentration until a ratio of one tetrameric enzyme to two double-stranded substrates was reached, further increase of the enzyme concentration then leads to a sharp decline of the reaction rate. These findings are interpreted in the following manner. (a) Two subunits of the EcoRI endonuclease co-operate in binding and possibly also in cleaving the palindromic substrate. (b) The enzymatic action of the EcoRI endonuclease is inhibited by excess enzyme, possibly due to unspecific binding of the enzyme-substrate complex. The self-inhibition of EcoRI endonuclease has also been observed with macromolecular substrates.
...
PMID:Two identical subunits of the EcoRI restriction endonuclease Co-operate in the binding and cleavage of the palindromic substrate. 628 84

The effect of glycerol on the specificity of DNA cleavage by the restriction endonuclease BamHI has been examined. In addition to the canonical G decreases from G-A-T-C-C site, BamHI cuts DNA at several sites that we have named noncanonical BamHI.1 sites. The number of BamHI.1 sites in simian virus 40 and pBR322 was determined to be 13 for each DNA. Cutting sites determined by DNA sequence analysis include G decreases from G-A-A-C-C, G decreases from G-C-T-C-C, G decreases from G-G-T-C-C, and G-A-A-T-C-C with the complementary strand sequence assignments of G-G-T-T-C-C, G-G-A-G-C-C, G-G-A-C-C-C, and G-G-A-T-T-C. The relaxation in specificity was related to hydrogen bond acceptor and donor sites in the recognition sequence, in an attempt to generate a model of BamHI recognition of cognate sites in DNA.
...
PMID:Sequence-specific endonuclease BamHI: relaxation of sequence recognition. 628 22

The junctions between contiguous right- and left-handed helical DNA segments in supercoiled plasmids are shown to exhibit both sequence- and superhelical-dependent conformational flexibility. The nonalternating (purine-pyrimidine) tetranucleotide d(G-A-T-C), which is imbedded within a (dC-dG) tract and exists as a junction at low-density values, may be adopting a left-handed helix under the influence of higher negative supercoiling. The effect of supercoiling on the transition from a right- to a left-handed state for (dC-dG)n inserts, where n = 16, 13, and 5, also was evaluated. Only moderate amounts of superhelicity (-0.03 to -0.075) are required for formation and stabilization of left-handed DNA even for the (dC-dG) region of 10 dC X dG base pairs. Finally, we demonstrate that junction formation within a BamHI restriction site causes a drastic inhibition (greater than 80%) of cleavage by this restriction endonuclease.
...
PMID:Conformational flexibility of junctions between contiguous B- and Z-DNAs in supercoiled plasmids. 630 83

A chromatin bound endonuclease (Mr:107,000) has been extracted and partially purified from the siliceous sponge Geodia cydonium. Disc gel electrophoresis showed that only one enzyme was present in the partially purified preparation which was able to degrade DNA and poly(A). The enzyme liberates oligonucleotides on incubation with poly(A), which are further degraded to yield the 5'-mononucleotide, which has a pI of 6.5 and a pH optimum of 7.5-8.0. Cations are not required for enzymic activity and EDTA does not inhibit the enzyme. Only iodosobenzoic acid was found to completely inhibit the enzyme. The enzyme hydrolysed poly(A), poly(U), poly(C), DNA, poly[d(A-T)], poly[d(G-C)], but not poly (dA) or poly(G).
...
PMID:Partial purification and properties of a chromatin bound endonuclease from the marine sponge Geodia cydonium. 631 74

The deoxyribooctanucleotide d(G-G-A-A-T-T-C-C), containing the recognition sequence for EcoRI, d(G-A-A-T-T-C), and analogs containing modified sugar moieties were tested for their activity in cleavage with EcoRI. These analogs, with replacement in the third position from the 5' end, were synthesized using 9-beta-D-arabinosyladenine (aA), 2'-deoxy-2'-fluoroadenosine (Afl) and adenosine (rA). Duplex formation by the three analogs was confirmed by measurements of ultraviolet/temperature profiles. It was found that EcoRI cleaved these duplexes less efficiently than d(G-G-A-A-T-T-C-C). The adenosine-containing analog d(G-G)-rA-d(A-T-T-C-C) was cleaved much more slowly than d(G-G)-aA-d(A-T-T-C-C) and d(G-G-Afl-A-T-T-C-C). The corresponding ribooctamer G-G-A-A-U-U-C-C showed a higher melting temperature than the deoxyoctamers but its duplex was not cleaved by this enzyme. An analog with 2'-deoxy-2'-fluoroguanosine at the second position was cleaved by the endonuclease faster than the natural deoxyoctamer.
...
PMID:Recognition by restriction endonuclease EcoRI of deoxyoctanucleotides containing modified sugar moieties. 632 Nov 78

A method is described for cutting DNA at specific sites that are 8 and 10 base pairs long. The DNA is first treated with a specific methylase, either the restriction-modification enzyme M. Taq I, which converts the 4-base sequence T-C-G-A to T-C-G-mA, or the similar enzyme M. Cla I, which converts the 6-base sequence A-T-C-G-A-T to A-T-C-G-mA-T. The DNA is then cleaved with Dpn I, a restriction endonuclease that recognizes the sequence G-mA-T-C. Dpn I is unique in that it cuts only DNA that is methylated at adenine in both strands of its recognition sequence. In DNAs that are not otherwise methylated at adenine in both strands of the sequence G-A-T-C, cleavage by Dpn I occurs only at the following sequences: in the case of M. Taq I methylation, 5' T-C-G-mA - T-C-G-mA 3' 3' mA-G-C - T-mA-G-C - T 5'; in the case of M. Cla I methylation, 5' A - T-C-G-mA - T-C-G-mA-T 3' 3' T-mA-G-C - T-mA-G-C - T-A 5'. Specific cutting and cloning at these methylase/Dpn I-generated sites is shown experimentally. Further, we describe how the above technique can be extended to generate Dpn I cleavage sites of up to 12 base pairs. In DNA that contains equal amounts of each base distributed at random, 8- and 10-base-pair recognition sequences occur, on the average, approximately once every 65,000 and 1,000,000 base pairs, respectively. Potential applications, including the development of cloning vectors and a rapid method for chromosome walking, are discussed.
...
PMID:Site-specific cleavage of DNA at 8- and 10-base-pair sequences. 632 93


<< Previous 1 2 3 4 5 6 Next >>

---