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141.
Isolation and characterization of anti-HIV peptides from Dorstenia contrajerva and Treculia obovoidea 总被引:2,自引:0,他引:2
Bokesch HR Charan RD Meragelman KM Beutler JA Gardella R O'Keefe BR McKee TC McMahon JB 《FEBS letters》2004,567(2-3):287-290
Using a high throughput screen based on the interaction of the HIV-1 gp41 ectodomain with the virucidal protein cyanovirin-N (CV-N), we isolated two new peptides which inhibited the binding of CV-N to gp41 and which subsequently showed anti-HIV activity in a whole cell assay. A 5-kDa (contrajervin) and 10 kDa (treculavirin) peptide were isolated from Dorstenia contrajerva and Treculia obovoidea, respectively. Treculavirin was composed of two subunits, each containing 50 amino acid residues, which are covalently linked by at least one disulfide bond between the subunits. Both peptides were shown to bind to gp41 and gp120 and to inhibit the cytopathic effects of HIV-1(RF) infection in a human T-lymphoblastoid cell line (CEM-SS). 相似文献
142.
Radha Charan Dash Angela M. Zaino M. Kyle Hadden 《Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms》2018,1861(6):594-602
The binding affinity between the histone 3 (H3) tail and the ADD domain of ATRX (ATRXADD) increases with the subsequent addition of methyl groups on lysine 9 on H3. To improve our understanding of how the difference in methylation state affects binding between H3 and the ATRXADD, we adopted a metadynamic approach to explore the recognition mechanism between the two proteins and identify the key intermolecular interactions that mediate this protein-peptide interaction (PPI). The non-methylated H3 peptide is recognized only by the PHD finger of ATRXADD while mono-, di-, and trimethylated H3 is recognized by both the PHD and GATA-like zinc finger of the domain. Furthermore, water molecules play an important role in orienting the lysine 9 anchor towards the GATA-like zinc finger, which results in stabilizing the lysine 9 binding pocket on ATRXADD. We compared our computational results against experimentally determined NMR and X-ray structures by demonstrating the RMSD, order parameter S2 and hydration number of the complex. The metadynamics data provide new insight into roles of water-bridges and the mechanisms through which K9 hydration stabilizes the H3K9me3:ATRXADD PPI, providing context for the high affinity demonstrated between this protein and peptide. 相似文献
143.
The phylogenetic origin of the bifunctional tyrosine-pathway protein in the enteric lineage of bacteria 总被引:5,自引:0,他引:5
Because bifunctional enzymes are distinctive and highly conserved products
of relatively infrequent gene-fusion events, they are particularly useful
markers to identify clusters of organisms at different hierarchical levels
of a phylogenetic tree. Within the subdivision of gram-negative bacteria
known as superfamily B, there are two distinctive types of tyrosine-pathway
dehydrogenases: (1) a broad- specificity dehydrogenase (recently termed
cyclohexadienyl dehydrogenase [CDH]) that can utilize either prephenate or
L-arogenate as alternative substrates and (2) a bifunctional CDH that also
posseses chorismate mutase activity. (T-proteins). The bifunctional
T-protein, thought to be encoded by fused ancestral genes for chorismate
mutase and CDH, was found to be present in enteric bacteria (Escherichia,
Shigella, Salmonella, Citrobacter, Klebsiella, Erwinia, Serratia,
Morganella, Cedecea, Kluyvera, Hafnia, Edwardsiella, Yersinia, and Proteus)
and in Aeromonas and Alteromonas. Outside of the latter "enteric lineage,"
the T-protein is absent in other major superfamily-B genera, such as
Pseudomonas (rRNA homology group I), Xanthomonas, Acinetobacter, and
Oceanospirillum. Hence, the T-protein must have evolved after the
divergence of the enteric and Oceanospirillum lineages.
3-Deoxy-D-arabino-heptulosonate 7-phosphate synthase-phe, an early-pathway
isozyme sensitive to feedback inhibition by L- phenylalanine, has been
found in each member of the enteric lineage examined. The absence of both
the T-protein and DAHP synthase-phe elsewhere in superfamily B indicates
the emergence of these character states at approximately the same
evolutionary time.
相似文献
144.
Molecular phylogenetics of Stenodermatini bat genera: congruence of data from nuclear and mitochondrial DNA 总被引:2,自引:1,他引:1
Van den Bussche RA; Baker RJ; Wichman HA; Hamilton MJ 《Molecular biology and evolution》1993,10(5):944-959
Within the tribe Stenodermatini the systematics of the complex of species
allied with the genus Artibeus has generated several alternative
phylogenetic hypotheses. The most recent treatment recognized four genera
(Artibeus, Dermanura, Enchisthenes, and Koopmania) and suggested that the
most recent common ancestor of these four genera would include the common
ancestor of all other currently recognized Stenodermatini genera except
Sturnira. To test this hypothesis, we examined an EcoRI-defined nuclear
satellite DNA repeat and 402 bp of DNA sequence variation from the
mitochondrial cytochrome b gene. Phylogenetic conclusions based on Southern
blot analyses, in situ hybridization, and mitochondrial DNA sequence data
indicate that Enchisthenes is not closely related to Dermanura, Artibeus,
or Koopmania and that Dermanura, Artibeus, and Koopmania shared a common
ancestor after diverging from the remainder of the Stenodermatini. If our
conclusions are correct, then justification for recognizing Dermanura and
Koopmania as generically distinct from Artibeus must be based on the
magnitude of difference that distinguishes each rather than on the
conclusion that to place them as congeneric with Artibeus creates a
paraphyletic taxon.
相似文献
145.
Pulmonary pseudallescheriosis was diagnosed in a two-months old calf. Pneumonic lungs with yellow-white nodules on the surfaces revealed granulomatous lesions microscopically. Septate, pleomorphic hyphae were present in the central caseated core with a bright eosinophilic periphery surrounded by polymorphonuclear cells and macrophages followed by a zone of epithelioid cells admixed with lymphocytes and plasma cells. The fungal agent was demonstrated by Grocott's silver methenamine staining. On isolation, morphologically it was found to be indistinguishable from that ofPseudallescheria boydii. It appears to be first report of fatal mycotic pneumonia in a calf due toP. boydii. The emphasis is given for further detailed investigation on this aspect in veterinary mycopathology. 相似文献
146.
Biotinyl-oligosaccharides are a relatively new generation of saccharide
probes that enable immobilization of desired oligosaccharides on
streptavidin matrices for studies of carbohydrate-protein interactions.
Here we describe the facile preparation of biotinyl-l-3-(2-naphthyl)-
alanine hydrazide (BNAH) derivatives of oligosaccharides, containing a
strong UV absorbing and fluorescent group, in which the ring of the
reducing-end monosaccharide is nonreduced. We evaluate reactivities of
immobilized BNAH- N -glycans with plant lectins that recognize aspects of
the oligosaccharide core or outer-arms. We make some comparisons with
2-amino-6-amidobiotinyl-pyridine (BAP) derivatives obtained by reductive
amination, and 6-(biotinyl)-aminocaproyl-hydrazide (BACH) derivatives which
have a longer spacer-arm. N -Glycan-BNAH and-BAP derivatives have, overall,
comparable reactivities with lectins which recognize N -glycan outer-arms
or the trimannosyl core, but only BNAH and BACH derivatives are bound by
lectins which recognize the non- reduced core. Moreover, with Pisum sativum
agglutinin (PSA) which additionally requires the fucosyl- N-
glycan-asparaginyl core for high affinity binding, the immobilized BNAH
derivative (which is an alanine hydrazide beta-glycoside) can substitute
for the natural beta- glycosylasparaginyl core, whereas the BACH derivative
(aminocaproyl- hydrazide-beta-glycoside) is less effective. BNAH is a
derivatization reagent of choice, therefore, for solid phase
carbohydrate-binding experiments with immobilized N -glycans.
相似文献
147.
Multidimensional heteronuclear NMR studies have been applied to the
resonance assignment and conformational analysis of 13C-enriched
Neu5Acalpha2-3Galbeta1-4Glc. It is demonstrated that three-dimensional
ROESY-HSQC experiments provide through-space distance restraints which
cannot be observed with conventional homonuclear 1H techniques due to
resonance overlap. In particular, connectivities demonstrating the
existence of the "anti" conformation about the Galbeta1-4Glc glycosidic
linkage are unambiguously observed. It is shown that 13C isotopic
enrichment of the trisaccharide at a level >95% enables straightforward
measurement of trans-glycosidic 1H-13C and 13C-13C coupling constants and a
Karplus-type relation is derived for the latter. In total 15 conformational
restraints were obtained for the trisaccharide in aqueous solution, all of
which were in excellent agreement with theoretical parameters computed from
a 5 ns molecular dynamics simulation of the glycan.
相似文献
148.
Changes in bronchial and pulmonary arterial blood flow with progressive tension pneumothorax 总被引:1,自引:0,他引:1
Carvalho Paula; Hildebrandt Jacob; Charan Nirmal B. 《Journal of applied physiology》1996,81(4):1664-1669
Carvalho, Paula, Jacob Hildebrandt, and Nirmal B. Charan.Changes in bronchial and pulmonary arterial blood flow with progressive tension pneumothorax. J. Appl.Physiol. 81(4): 1664-1669, 1996.We studied theeffects of unilateral tension pneumothorax and its release on bronchialand pulmonary arterial blood flow and gas exchange in 10 adultanesthetized and mechanically ventilated sheep with chronicallyimplanted ultrasonic flow probes. Right pleural pressure (Ppl) wasincreased in two steps from 5 to 10 and 25 cmH2O and then decreased to 10 and5 cmH2O. Each level of Pplwas maintained for 5 min. Bronchial blood flow, right and leftpulmonary arterial flows, cardiac output(T),hemodynamic measurements, and arterial blood gases were obtained at theend of each period. Pneumothorax resulted in a 66% decrease inT, bronchialblood flow decreased by 84%, and right pulmonary arterial flowdecreased by 80% at Ppl of 25 cmH2O(P < 0.001). At peak Ppl, themajority ofT was due toblood flow through the left pulmonary artery. With resolution ofpneumothorax, hemodynamic parameters normalized, although abnormalitiesin gas exchange persisted for 60-90 min after recovery and wereassociated with a decrease in total respiratory compliance. 相似文献
149.
150.