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Topic: Cyclobutane

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Cyclopropane

Cyclopentane

Cycloalkane

Cyclohexane

Alkene

Alkyl

Aromatic hydrocarbon

Alkyne

Madonna and Child

Hygroscopic

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Background check

	Investigation of UVC Induced DNA Damage Formation and Photolyase Catalyzed Repair of Cyclobutane Pyrimidine Dimers - ...
		Investigation of UVC Induced DNA Damage Formation and Photolyase Catalyzed Repair of Cyclobutane Pyrimidine Dimers - Digitale Hochschulschriften der LMU
		Three kinds of photoproducts are mainly formed, namely: cyclobutane pyrimidine dimers (CPD), pyrimidine-(6-4)-pyrimidone dimer [(6-4)PP] and the Dewar valence isomer of (6-4)PP lesion.
		The formation of these photolesions is a major cause of cell death (aging) and fatal disease like skin cancer. A part of this research was performed to investigate the formation and characterization of DNA-lesions under UVC radiation.
	edoc.ub.uni-muenchen.de /3195 (506 words)

	[No title]
		These include cyclobutane type dimers arising from the cycloaddition of the C5-C6 double bond of two adjacent pyrimidines, and the pyrimidine (6-4) pyrimidone adducts which result from the addition of the C5-C6 double of the 5'-end pyrimidine to the C4 carbonyl or imine group of the 3'-end pyrimidine.
		This is indicative of a lower stability of the cyclobutane ring of the anti cyclobutadithymine with respect to that of the syn diastereoisomers.
		In contrast, the pseudo-molecular ion of the (6-4) photoproduct and of its Dewar valence isomer yielded a daughter ion at m/z=432.
	www.laubscherlabs.com /Application/Thymine.txt (6272 words)

	Cyclobutane - Wikipedia, the free encyclopedia
		Cyclobutane is a gas and commercially available as a liquefied gas.
		Despite inherent strain the cyclobutane motive is not an alien to molecules found in nature.
		One unusual example is pentacycloanammoxic acid which is a ladderane comprised of 5 fused cyclobutane units.
	en.wikipedia.org /wiki/Cyclobutane (300 words)

	MOLECULAR STUDIES OF ULTRAVIOLET RADIATION EFFECTS ON MARINE BACTERIA
		Cyclobutane dimers were then quantified in the extracted DNA using the radioimmunoassay methodology developed in one of our labs (Mitchell et al., 1985).
		During a series of research cruises in the Northern Gulf of Mexico we examined the relative proportion of DNA damage in the bacterioplankton size fraction (<0.8m) and what we are operationally defining as the eukayotic planktonic size fraction (>0.8 m).
		Cyclobutane dimers were determined in each DNA extract via radio-immuno assay (Mitchell et al., 1985).
	www.nbiap.vt.edu /brarg/brasym94/jeffrey.htm (2304 words)

	Electrostatic Potential Surfaces for the Cyclobutane Uracil Dimer
		The overall shape and charge distribution of the cyclobutane uracil dimer suggest a binding mode in which the electrostatic potential pattern in the dimer is matched with the asymmetric distribution of polar and nonpolar amino acid residues in the putative active site of DNA photolyase.
		The cis, syn Cyclobutane Uracil Dimer Radical Cation
		The cis, syn Cyclobutane Uracil Dimer Radical Anion
	www.netsci-journal.com /97v1/97008/index.htm (240 words)

	[Frontiers in Bioscience 2, d538-551, November 1, 1997] (Site not responding. Last check: )
		Cyclobutane dimers are formed between the C-4 and C-5 carbon atoms of any two adjacent pyrimidines; the double bonds become saturated to produce a four-membered ring (3).
		Cyclobutane dimers are produced overall three times as often as (6-4) photoproducts, although the ratio depends on the DNA sequence and the chromatin environment (10).
		In the C-C cyclobutane dimer, a CCTT transition occurs; two A residues are placed opposite the dimer by default in the place of two G residues.
	www.bioscience.org /1997/v2/d/soehnge/3.htm (1552 words)

	On the formation of cyclobutane pyrimidine dimers in UV-irradiated DNA: Why are thymines more reactive?[para] ... (Site not responding. Last check: )
		The reaction pathways for thermal and photochemical formation of cyclobutane pyrimidine dimers in DNA are explored using density functional theory techniques.
		It is shown that the photocycloaddition of thymines is facilitated by the fact that the S^sub 1^ state of the corresponding reactant complex lies comparatively high in energy.
		Cyclobutane pyrimidine dimers (CPD) are the major photoproducts observed in UV-irradiated DNA and have been correlated with cell lethality, mutagenesis and the development of skin cancer (1,2).
	www.findarticles.com /p/articles/mi_qa3931/is_200308/ai_n9301618 (841 words)

	ARKAT USA, Inc.
		An approach to the synthesis of cyclobutane fused γ-butyrolactones is described.
		a general protocol for the synthesis of the cyclobutane fused γ-butyro lactones and its application in a formal synthesis of grandisol 1.
		The synthetic potential of the cyclobutane fused γ-butyro lactone is demonstrated by a formal synthesis of grandisol 1 (Scheme 2).
	www.arkat-usa.org /home.aspx?VIEW=MANUSCRIPT&MSID=214 (2683 words)

	UABSOSG-Cyclobutanes
		The use of pheromones, either in combination with traps or by emission of fake signals to interfere the sexual pairing (and hence the proliferation), is an environmentally friendly alternative to the use of pesticides.
		Despite more than 100 chiral pheromones have been isolated and characterized at present, very few are known presenting a cyclobutane in their structure.
		Since they were isolated, the cyclobutane structure and biological activity of these compounds have attracted the interest of many synthetic chemists.
	einstein.uab.es /_c_gr_soe/soe/cyclobutanes.htm (769 words)

	The cis, syn Cyclobutane Uracil Dimer
		The Becke3LYP/6-31G* optimized structure of the cis,syn cyclobutane uracil dimer 1 is shown in Figure 3.
		This is in marked contrast to the planar cyclobutane ring obtained by semiempirical calculations.
		[8] Although the force constants for the dihedral angles in the cyclobutane ring are relatively small, it is clear from the helical structure of DNA and the available X-ray crystallographic data that the puckered cyclobutane ring is present in all known derivatives of 1.
	www.netsci-journal.com /97v1/97008/page2.html (629 words)

	Cycloalkanes
		The bond angles in cyclopropane are those of an equilateral triangle, 60 degrees, as compared to the tetrahedral bond angle of 109.5 degrees.
		Cyclobutane is a square structure; it is less reactive than cyclopropane because the bond angle strain is less, 90 degrees compared to the tetrahedral bond angle of 109.5 degrees.
		Cycloalkanes with a single ring are named analogously to their normal alkane counterpart of the same carbon count: cyclopropane, cyclobutane, cyclopentane, cyclohexane, etc. The larger cycloalkanes, with greater than 20 carbon atoms are typically called cycloparaffins.
	www.3rd1000.com /chem301/chem301k.htm (867 words)

	Iverson's CH610A/ Fall 97 - POTD: 9/25/97 (Site not responding. Last check: )
		Here is cyclobutane, which is more stable than cyclopropane.
		Unlike cyclopropane, which is flat, cyclobutane puckers to minimize torsional strain.
		There is no evidence of steric strain for cyclobutane, as can be seen by inspecting the space-filling model.
	www.chem.tamu.edu /organic/Fall98/cyclic-1.html (369 words)

	Chemical synthesis and translesion replication of a cis-syn cyclobutane thymine-uracil dimer -- Takasawa et al. 32 (5): ...
		cyclobutane pyrimidine dimer (CPD) with an adjacent pyrimidine
		cyclobutane TC dimer (T[]C) is converted to the TU dimer (T[]U) by this deamination, and C
		Lemaire,D.G.E. and Ruzsicska,B.P. (1993) Kinetic analysis of the deamination reactions of cyclobutane dimers of thymidylyl-3',5'-2'-deoxycytidine and 2'-deoxycytidylyl-3',5'-thymidine.
	nar.oxfordjournals.org /cgi/content/full/32/5/1738 (4846 words)

	Inter-strand photoproducts are produced in high yield within A-DNA exposed to UVC radiation -- Douki et al. 31 (12): ...
		cyclobutane dimers were also produced in significant yields.
		For the trans,syn and cis,anti cyclobutane dimers, the (6–4) and the spore photoproducts, reported values represent the sum of the yield of the two diastereoisomers.
		Effect of the presence of ethanol on the yield of formation of intra- and inter-strand spore photoproducts and inter-strand trans,anti thymine cyclobutane dimer.
	nar.oxfordjournals.org /cgi/content/full/31/12/3134 (5483 words)

	Fifth International Electronic Conference on Synthetic Organic Chemistry
		The repair of T<>T in bacterials is achieved by the dimer specific repair enzyme photolyase through a direct one-electron reduction followed by cycloreversion of the resulting unstable cyclobutane radical anion and subsequent oxidation to the thymine monomers.
		It was shown that the cleavage of the cyclobutane pyrimidine dimer could also proceed through an oxidative pathway, since the cyclobutane radical cation is similarly unstable.
		With respect to the uracil dimer 2a the cyclobutane ring in the thymine dimer 4a is significantly more crowded by the two additional methyl groups.
	www.mdpi.org /ecsoc/ecsoc-5/Papers/c0005/c0005.htm (1660 words)

	Respective Roles of Cyclobutane Pyrimidine Dimers, (6-4)Photoproducts, and Minor Photoproducts in Ultraviolet ... (Site not responding. Last check: )
		Respective Roles of Cyclobutane Pyrimidine Dimers, (6-4)Photoproducts, and Minor Photoproducts in Ultraviolet Mutagenesis of Repair-deficient Xeroderma Pigmentosum A Cells -- Otoshi et al.
		Marionnet C., Armier J., Sarasin A., Stary A. Cyclobutane pyrimidine dimers are the main mutagenic DNA photoproducts in DNA repair-deficient Trichothiodystrophy cells.
		Cyclobutane Pyrimidine Dimers Are Responsible for the Vast Majority of Mutations Induced by UVB Irradiation in Mammalian Cells
	cancerres.aacrjournals.org /cgi/content/full/60/6/1729 (4720 words)

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