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Topic: Ribozyme

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Ribonuclease

RNA

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	Ribozyme - Wikipedia, the free encyclopedia
		Investigators studying the origin of life have produced ribozymes in the laboratory that are capable of catalyzing their own synthesis under very specific conditions.
		This ribozyme was found in the intron of an RNA transcript and removed itself from the transcript.
		Although most ribozymes are quite rare in the cell, their roles are sometimes essential to life.
	en.wikipedia.org /wiki/Ribozyme (556 words)

	Ribozyme Enzymology
		Ribozymes are antisense RNA molecules that have catalytic activity.
		The name of hammerhead ribozyme is given by the similarity between its secondary structure and the shape of a hammerhead.
		However, most ribozymes can be chemically engineered to cleave RNA in trans by separating the catalytic domain from ribozyme and attaching recognition (i.e., antisense) arms to the catalytic center, in order to target to a substrate.
	academic.brooklyn.cuny.edu /chem/zhuang/QD/toppage1.htm (597 words)

	Ribozymes: molecular scissors for investigating genetic function (Site not responding. Last check: 2007-10-05)
		Ribozymes are molecular scissors that cut RNA, the molecular messages given by genes in order to produce proteins.
		Obviously when the ribozyme is introduced into the cell, the researcher does not want the ribozyme to cut all the RNA messengers since a large number of genes will be turned off.
		By designing ribozymes that target the RNA messenger of certain genetic sequences in muscle cells that have been cultured under special conditions, it is hoped that changes in these cultured cells will be observed that resemble the changes that are seen in Spinal Muscular Atrophy patients.
	www.madsci.org /dtm/ribozyme.html (432 words)

	Kinetic Mechanism of the Hairpin Ribozyme. IDENTIFICATION AND CHARACTERIZATION OF TWO NONEXCHANGEABLE CONFORMATIONS -- ...
		Except in the case of the wt ribozyme, approximately 75% of the substrate was cleaved in the fast phase of the reaction.
		Ribozyme nomenclature is as defined in the Introduction and Fig.
		that the conformational heterogeneity of the wt hairpin ribozyme
	www.jbc.org /cgi/content/full/272/21/13629 (6993 words)

	RIBOZYME SNAPSHOTS
		The discovery of ribozymes overturned the DNA-dogma that only proteins can trigger cell activity and helped clarify the "DNA/RNA-chicken or egg" questions about life's origins, since they are able to provide both the genetic code and the necessary activity for reproduction in one compact package.
		Ribozymes of the type depicted in this new research are already being developed to function as precision scissors that snip out flawed genetic segments from other RNA molecules and splice in corrected versions.
		The self-splicing ribozyme is by far the largest RNA molecule to have part of its 3-D chemical structure solved by X-ray crystallography in atomic detail.
	www.accessexcellence.org /WN/SUA08/rna1096.html (841 words)

	Snapshots of Ribozyme Reaction States Reveal Structural Switch
		The delta virus ribozyme is unique, however, in that once the RNA is cleaved, the ribozyme is somehow inactivated, "switching off" and preventing further RNA cleavage or re-ligation of the separated RNA strands.
		Together with supporting biochemical data, these structures suggest that the cytidine from the ribozyme activates the RNA for self-cleavage, while a magnesium-bound water molecule stabilizes the RNA as the bond is broken.
		This unique quality of the HDV ribozyme to slice specific RNA molecules and then inactivate itself provides a mechanistic explanation for its activity during the HDV viral life cycle, information that could be useful in developing antiviral therapies that target the ribozyme.
	www-als.lbl.gov /als/science/sci_archive/86ribozyme.html (958 words)

	Specific Inhibition of Macrophage TNF-{alpha} Expression by In Vivo Ribozyme Treatment -- Kisich et al. 163 (4): 2008 ...
		ribozyme activity was not detectable in the absence of Mg and was inhibited by low temperature (20, 21).
		The ribozyme was designed to be placed near the 3' end of the transcript and cleave the 5' portion at the site of the arrow.
		P ribozymes were complexed with transfection lipid and 1 ml of the complex injected i.p.
	www.jimmunol.org /cgi/content/full/163/4/2008 (4628 words)

	HHMI News: Evidence that a Ribozyme Evolved Multiple Times
		The evidence for multiple origins of the hammerhead ribozyme, which is found in organisms as diverse as plant viruses, newts, schistosomes and cave crickets, was published in the November 1, 2001, issue of the journal Nature by HHMI investigator Jack W. ostak and Kourosh Salehi-Ashtiani at Massachusetts General Hospital.
		According to Szostak, the evidence that the hammerhead ribozyme might have had multiple origins arose from experiments in which the scientists were attempting to create a faster self-cleaving ribozyme for use in research.
		Szostak and his colleagues plan to continue their efforts to achieve faster self-cleaving ribozymes, which might be useful for in vivo studies of cell function as well as therapeutics.
	www.hhmi.org /news/szostak2.html (1033 words)

	Inhibition of Viral Replication by Ribozyme: Mutational Analysis of the Site and Mechanism of Antiviral Activity -- ...
		vitro cleavage assays with in vitro-transcribed ribozymes and
		A hammerhead ribozyme inhibits the proliferation of an RNA coliphage SP in Escherichia coli.
		Folding of the four-way RNA junction of the hairpin ribozyme.
	jvi.asm.org /cgi/content/full/79/6/3728 (6250 words)

	Ribozyme compromise of adrenomedullin mRNA reveals a physiological role in the regulation of water intake -- Taylor and ...
		Ribozyme treatment led to a decrease in full-length AM RNA levels that was visible by 2 h after treatment (Fig.
		Ribozyme rescue of photoreceptor cells in P23H transgenic rats: long-term survival and late-stage therapy.
		Ribozyme rescue of photoreceptor cells in a transgenic rat model of autosomal dominant retinitis pigmentosa.
	ajpregu.physiology.org /cgi/content/full/282/6/R1739 (4046 words)

	HHMI News: Ribozymes Come Ready for Action
		A structural model of the ribozyme from the human pathogen hepatitis delta virus.
		Scientists have since discovered more than 500 ribozymes in a diverse range of organisms and have found that they share many similarities with their more widespread protein cousins, enzymes.
		In the October 8, 1998, issue of Nature, HHMI investigator Jennifer Doudna and colleagues from Yale University detail the structure of a smaller ribozyme from the human pathogen, hepatitis delta virus (HDV).
	www.hhmi.org /news/ribozyme.html (795 words)

	Trans-splicing of a mutated glycosylasparaginase mRNA sequence by a group I ribozyme deficient in hydrolysis -- ... (Site not responding. Last check: 2007-10-05)
		DiGIR2 is the splicing ribozyme derived from the twin-ribozyme
		The ribozyme catalyzes the coupled cleavage of mutated mRNA and the ligation of the restorative 3' exon to the remaining 5' exon.
		P9.2 AGU ribozymes added in the trans-splicing reactions was approximately identical, the addition of the ribozyme band (RNA 4) in the fractions denominator gave approximately identical comparative results (data not shown).
	content.febsjournal.org /cgi/content/full/271/23-24/4932 (2886 words)

	Kinetic analysis of ribozyme-substrate complex formation in yeast -- YADAVA et al. 10 (5): 863 -- RNA
		Additional ribozyme and substrate variants were examined that formed H1 helices ranging from three base pairs (R23) to six base pairs (R26) in length and with base pair substitutions that enhanced the stability of H2 (Fig.
		Donahue, C.P. and Fedor, M.J. Kinetics of hairpin ribozyme cleavage in yeast.
		Donahue, C.P., Yadava, R.S., Nesbitt, S.M., and Fedor, M.J. The kinetic mechanism of the hairpin ribozyme in vivo: Influence of RNA helix stability on intracellular cleavage kinetics.
	www.rnajournal.org /cgi/content/full/10/5/863 (7150 words)

	Induction of Apoptosis in Oral Cancer Cells by an Anti-bcl-2 Ribozyme Delivered by an Adenovirus Vector -- Gibson et ... (Site not responding. Last check: 2007-10-05)
		of the ribozyme was described earlier (28), and it is illustrated
		consensus sequence of a ribozyme and was complementary to the
		A, effects of the ribozyme:target ratio when the target and ribozyme were mixed for 60 min.
	clincancerres.aacrjournals.org /cgi/content/full/6/1/213 (5452 words)

	Functional colocalization of ribozymes and target mRNAs in Drosophila oocytes -- LEE et al. 15 (13): 2390 -- The FASEB ...
		Detection of ribozyme RNA distribution in ovaries directed by the osk (A) or bcd (B) 3'UTR using in situ hybridization.
		Colocalization (A) of the ribozyme to the target lacZ mRNA using the synonymous osk3'UTR (osk-osk) was more inhibitory to ß-galactosidase activity than the noncolocalized (osk-bcd) (B) or the negative control harboring GFP instead of the ribozyme (osk-GFP) (C).
		The asterisk indicates that the ribozyme construct was the inactive mutant.
	www.fasebj.org /cgi/content/full/15/13/2390 (6190 words)

	Adenoviral Delivery of a Leukocyte-Type 12 Lipoxygenase Ribozyme Inhibits Effects of Glucose and Platelet-Derived ...
		Ribozymes are catalytically active RNA molecules with the capacity
		ribozyme sequence as the probe confirmed the presence of the ribozyme
		Inhibition of PSMC migration in response to PDGF by 12LO ribozyme.
	circres.ahajournals.org /cgi/content/full/88/7/659 (5106 words)

	HIV-1 LTR as a target for synthetic ribozyme-mediated inhibition of gene expression: site selection and inhibition in ...
		Ribozymes are RNA-based enzymes that bind to and cleave RNA
		degree of cleavage was observed with ribozyme Rz109.
		Luciferase activity of cells, transfected with the inverted form of the ribozyme, was defined as 100% control.
	nar.oxfordjournals.org /cgi/content/full/28/21/4059 (5260 words)

	Ribozyme-mediated down-regulation of survivin expression sensitizes human melanoma cells to topotecan in vitro and in ...
		The endogenous presence of the ribozymes in tumors grown in
		Ribozyme expression in tumors grown in nude mice.
		Ribozyme expression was detected by RT–PCR in tissue samples obtained from tumors originating from JR8 cells transfected with the active ribozyme (JR8/RZsurv) or with the mutant ribozyme (JR8/mutRZsurv).
	carcin.oxfordjournals.org /cgi/content/full/25/7/1129 (4808 words)

	Characterization of a mobilization-competent simian immunodeficiency virus (SIV) vector containing a ribozyme against ...
		The anti-SIV pol ribozyme vector was derived from the
		Cell supernatants (100 µl) from p1T (antisense RT ribozyme), p4T (sense RT ribozyme), p5T (no ribozyme) and mock-transfected CEMx174 cell cultures were filter-sterilized through a 0·2 µm filter, passaged in uninfected CEMx174 cells and analysed over 14 days.
		Lane 1, detection of p4T anti-SIV-RT sense ribozyme vector in viral RNA from p4T-transfected cell culture supernatant.
	vir.sgmjournals.org /cgi/content/full/85/6/1489 (4014 words)

	Inhibition of Viral Replication by Ribozyme: Mutational Analysis of the Site and Mechanism of Antiviral Activity.
		A hairpin ribozyme targeting G575 of the Sindbis virus genomic RNA was designed and cloned into a minimized alphavirus amplicon vector.
		Single mutations in the virus or ribozyme decreased the efficacy of the ribozyme's inhibition of viral replication, and compensatory mutations restored it.
		The results show that most of the antiviral activity of ribozymes is due to ribozyme-catalyzed cleavage at the targeted RNA sequence, but some additional inhibition seems to occur through an antisense mechanism.
	www.euchromatin.com /Burke01.htm (3142 words)

	Disruption of Glucose Sensing and Insulin Secretion by Ribozyme Kir6.2-Gene Targeting in Insulin-Secreting Cells -- Li ...
		B, The time profile shows that ribozyme treatment (2.7 moi) produced evident inhibition of insulin secretion on d 1, reached the maximal level on d 2–3, and started declining on d 4 of glucose stimulation at 10.0, 16.7, and 25.0 m
		Hormes R, Sczakiel G 2002 The size of hammerhead ribozymes is related to cleavage kinetics: the role of substrate length.
		Murray JB, Seyhan AA, Walter NG, Burke JM, Scott WG 1998 The hammerhead, hairpin and VS ribozymes are catalytically proficient in monovalent cations alone.
	endo.endojournals.org /cgi/content/full/145/9/4408 (4140 words)

	Longevity Report 91
		Telomerase expression is usually switched on in cancer cells; inappropriate over-expression of telomerase being one of the critical mutations a cancer cell requires to replicate unchecked.
		Ribozyme — A small number of important non-proteonomic enzymes are formed from nucleotides, not amino acids.
		Ribozymes are believed to be the most ancient of all enzymes, evolving before the more numerous proteonomic enzymes, and still play a pivotal role in metabolism.
	mcp.longevity-report.com (15506 words)

	Hairpin - Film Fest Journal: Ornamental Hairpin, 1941
		However, it has been shown that a hairpin capture probe, which contains a duplex Hairpin capture probes typically consist of three major parts: 1.
		Stability of hairpin ribozyme tertiary structure is governed by
		The equilibrium distributions of hairpin ribozyme conformational isomers have been examined by time-resolved fluorescence resonance energy transfer.
	virginal.surferfind.com /?q=virginal-hairpin (183 words)

	Current Research Focusing on Euchromatin Within the Cell Nucleus.
		Zhang Z, and Burke JM, "Inhibition of Viral Replication by Ribozyme: Mutational Analysis of the Site and Mechanism of Antiviral Activity".
		Schultes EA, and Bartel DP, "One Sequence, Two Ribozymes: Implications for the Emergence of New Ribozyme Folds".
		Van Houdt H, Van Montagu M, and Depicker A, "Both Sense and Antisense RNAs are Targets for the Sense Transgene-Induced Posttranscriptional Silencing Mechanism".
	www.euchromatin.net /current1.html (10576 words)

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