The structure of the benzilic acid rearrangement product of 3.alpha.,17.beta.-diacetoxy-11-hydroxy-12-oxo-5.beta.-androst-9(11)-ene. An unusual structure with three five-membered rings cis-fused

1968 ◽  
Vol 90 (8) ◽  
pp. 2144-2149 ◽  
Author(s):  
James S. McKechnie ◽  
Iain C. Paul
Keyword(s):  
Rearrangement Product ◽  
Unusual Structure ◽  
Benzilic Acid

Fine Structure of Interdental Cells in the Mouse Cochlea

1970 ◽  
Vol 28 ◽  
pp. 140-141
Author(s):  
Roberta M. Bruck
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Young Adult ◽  
Uranyl Acetate ◽  
Ground Substance ◽  
Tectorial Membrane ◽  
Lead Citrate ◽  
Unusual Structure ◽  
Thin Sections ◽  
Collagenous Fibers

An unusual structure in the cochlea is the spiral limbus; this periosteal tissue consists of stellate fibroblasts and collagenous fibers embedded in a translucent ground substance. The collagenous fibers are arranged in vertical columns (the auditory teeth of Haschke). Between the auditory teeth are interdental furrows in which the interdental cells are situated. These epithelial cells supposedly secrete the tectorial membrane.The fine structure of interdental cells in the rat was reported by Iurato (1962). Since the mouse appears to be different, a description of the fine structure of mouse interdental cells' is presented. Young adult C57BL/6J mice were perfused intervascularly with 1% paraformaldehyde/ 1.25% glutaraldehyde in .1M phosphate buffer (pH7.2-7.4). Intact cochlea were decalcified in .1M EDTA by the method of Baird (1967), postosmicated, dehydrated, and embedded in Araldite. Thin sections stained with uranyl acetate and lead citrate were examined in a Phillips EM-200 electron microscope.

Reaction of 1,4-dibromohexafluoro-2-butene with O- and N-nucleophiles

1988 ◽  
Vol 53 (3) ◽  
pp. 619-625 ◽  
Author(s):  
Ivan Hemer ◽  
Věra Moravcová ◽  
Václav Dědek
Keyword(s):  
Kinetic Study ◽  
Sodium Methoxide ◽  
Allylic Rearrangement ◽  
Rearrangement Product

Reaction of 1,4-dibromohexafluoro-2-butene (I) with sodium methoxide, ethoxide or isopropoxide in the corresponding alcohols proceeds with allylic rearrangement under formation of 3-alkoxy-4-bromohexafluoro-1-butenes II-IV. A kinetic study has proven the SN2’ mechanism for reaction of I with potassium phenoxide leading to 4-bromo-3-phenoxyhexafluoro-1-butene (V). Also the reaction of I with ammonia, affording 3-amino-4-bromo-2,4,4-trifluoro-2-butenenitrile (IX), is compatible with the allylic rearrangement by SN2’ mechanism. On the contrary, reaction of I with diethylamine gave no rearrangement product and, after hydrolysis, afforded N,N-diethyl-4-bromo-2,3,3,4,4-pentafluorobutanamide (XVI) and N,N-diethyl-4-bromo-2,3,4,4-tetrafluoro-2-butenamide (XVII) in the ratio 85:15.

An Approach to the Carbocyclic Skeleton of Shinjudilactone Using a Benzilic Acid Rearrangement1,2

1988 ◽  
Vol 18 (1) ◽  
pp. 13-20 ◽  
Author(s):  
Norma K. Dunlap ◽  
Raymond S. Gross ◽  
David S. Watt
Keyword(s):  
Benzilic Acid ◽  
Carbocyclic Skeleton

scholarly journals Flavivirus NS1 and Its Potential in Vaccine Development

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 622
Author(s):  
Kassandra L. Carpio ◽  
Alan D. T. Barrett
Keyword(s):  
Vaccine Development ◽  
Virus Assembly ◽  
Ns1 Protein ◽  
Human Pathogens ◽  
Unusual Structure ◽  
Replication Complex ◽  
Virus Challenge ◽  
Humoral Immune ◽  
Tick Borne Encephalitis ◽  
Flavivirus Infection

The Flavivirus genus contains many important human pathogens, including dengue, Japanese encephalitis (JE), tick-borne encephalitis (TBE), West Nile (WN), yellow fever (YF) and Zika (ZIK) viruses. While there are effective vaccines for a few flavivirus diseases (JE, TBE and YF), the majority do not have vaccines, including WN and ZIK. The flavivirus nonstructural 1 (NS1) protein has an unusual structure–function because it is glycosylated and forms different structures to facilitate different roles intracellularly and extracellularly, including roles in the replication complex, assisting in virus assembly, and complement antagonism. It also plays a role in protective immunity through antibody-mediated cellular cytotoxicity, and anti-NS1 antibodies elicit passive protection in animal models against a virus challenge. Historically, NS1 has been used as a diagnostic marker for the flavivirus infection due to its complement fixing properties and specificity. Its role in disease pathogenesis, and the strong humoral immune response resulting from infection, makes NS1 an excellent target for inclusion in candidate flavivirus vaccines.

scholarly journals The unusual structure of the PiggyMac cysteine-rich domain reveals zinc finger diversity in PiggyBac-related transposases

Mobile DNA ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marc Guérineau ◽  
Luiza Bessa ◽  
Séverine Moriau ◽  
Ewen Lescop ◽  
François Bontems ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Dna Cleavage ◽  
Trichoplusia Ni ◽  
Catalytic Domain ◽  
Structural Diversity ◽  
Paramecium Tetraurelia ◽  
Lysine Methylation ◽  
Unusual Structure ◽  
Rich Domain ◽  
Cysteine Rich Domain

Abstract Background Transposons are mobile genetic elements that colonize genomes and drive their plasticity in all organisms. DNA transposon-encoded transposases bind to the ends of their cognate transposons and catalyze their movement. In some cases, exaptation of transposon genes has allowed novel cellular functions to emerge. The PiggyMac (Pgm) endonuclease of the ciliate Paramecium tetraurelia is a domesticated transposase from the PiggyBac family. It carries a core catalytic domain typical of PiggyBac-related transposases and a short cysteine-rich domain (CRD), flanked by N- and C-terminal extensions. During sexual processes Pgm catalyzes programmed genome rearrangements (PGR) that eliminate ~ 30% of germline DNA from the somatic genome at each generation. How Pgm recognizes its DNA cleavage sites in chromatin is unclear and the structure-function relationships of its different domains have remained elusive. Results We provide insight into Pgm structure by determining the fold adopted by its CRD, an essential domain required for PGR. Using Nuclear Magnetic Resonance, we show that the Pgm CRD binds two Zn2+ ions and forms an unusual binuclear cross-brace zinc finger, with a circularly permutated treble-clef fold flanked by two flexible arms. The Pgm CRD structure clearly differs from that of several other PiggyBac-related transposases, among which is the well-studied PB transposase from Trichoplusia ni. Instead, the arrangement of cysteines and histidines in the primary sequence of the Pgm CRD resembles that of active transposases from piggyBac-like elements found in other species and of human PiggyBac-derived domesticated transposases. We show that, unlike the PB CRD, the Pgm CRD does not bind DNA. Instead, it interacts weakly with the N-terminus of histone H3, whatever its lysine methylation state. Conclusions The present study points to the structural diversity of the CRD among transposases from the PiggyBac family and their domesticated derivatives, and highlights the diverse interactions this domain may establish with chromatin, from sequence-specific DNA binding to contacts with histone tails. Our data suggest that the Pgm CRD fold, whose unusual arrangement of cysteines and histidines is found in all PiggyBac-related domesticated transposases from Paramecium and Tetrahymena, was already present in the ancestral active transposase that gave rise to ciliate domesticated proteins.

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