Chemical evidence

In order to explore the importance of the Antheroporum genus in pharmaceutical applications, two bioactivities of A. harmandii plant extracts have been evaluated in this study. Antimicrobial and antioxidant activities of A. harmandii extracts will provide evidences for further chemical composition studies to detect new bioactive compounds from this species.

9p dianmotminh02 03-05-2024 6 2   Download

A new 3
-acetoxy-urs-23,28,30-trioic acid, named acantrifoic acid B (1), has been isolated from the leaves of Acanthopanax trifoliatus. Its chemical structure has been characterized on the basis of spectral and chemical evidence.

4p cumeo4000 01-08-2018 21 0   Download

From the ethanolic extract of the fresh leaves of Crinum latifolium L. four compounds: methyl (E)-p-hydroxycinnamate, ethyl (E)-3,4-dihydroxycinnamate, kaempferol-3-O- -D-glucopyrano- side, and kaempferol-3-4’-di-O- -D-glucopyranoside were isolated and identified. Their structures were established by analysis of chemical and spectral evidence.

4p uocvong04 24-09-2015 54 4   Download

Five flavonoids along with -sitosterol were isolated from the leaves of Polygonum hydropiper L. (Polygonaceae). Four flavonoids were identified as quercetin, quercetin-3-O- -L- rhamnoside (quercitrin), quercetin-3-sulphate and (+)-catechin. Their structures were established on the basis of chemical evidence and spectroscopic techniques, including 2D NMR methods.

5p uocvong04 24-09-2015 57 2   Download

A new 3 -acetoxy-urs-23,28,30-trioic acid, named acantrifoic acid B (1), has been isolated from the leaves of Acanthopanax trifoliatus. Its chemical structure has been characterized on the basis of spectral and chemical evidence.

4p uocvong04 24-09-2015 34 3   Download

A splicing factor SF2/ASF is a natural substrate for the kinase activity of human topoisomerase I. This study demonstrates that SF2/ASF inhibits DNA cleavage by human topoisomerase I induced by the anti-cancer agent camptothecin. The inhibition is independent of the phosphorylation status of SF2/ASF. We show that the inhibition did not result from binding of SF2/ASF to DNA that would hinder interactions between topoisomerase I and DNA. Neither it was a consequence of a loss of sensitivity of the enzyme to camptothecin.

7p research12 01-06-2013 39 5   Download

A eukaryotic-type protein serine/threonine kinase, PknA, was cloned from Mycobacterium tuberculosis strain H37Ra. Sequencing of the clone indicated 100% identity with the published pknA sequence of M. tuberculosis strain H37Rv. PknA fused to maltose-binding protein was expressed in Escherichia coli; it exhibited a molecular mass of % 97 kDa. The fusion protein was purified from the soluble fraction by affinity chromatography using amylose resin.

8p research12 01-06-2013 41 3   Download

The apparent molecular mass of human milk bile salt-stimulated lipase (BSSL) varies between mothers. The molecular basis for this is unknown, but indirect evidence has suggested the di€erences to reside in a region of repeats located in the C-terminal part of the protein. We here report that a polymorphism within exon 11 of the BSSLgene is the explanation for the molecular variants of BSSL found in milk.

9p research12 01-06-2013 44 4   Download

Natively unfolded or intrinsically unstructured proteins constitute a unique group of the protein kingdom. The evolutionary persistence of such proteins represents strong evidence in the favor of their importance and raises intriguing questions about the role of protein disorders in biological processes. Additionally, natively unfolded pro-teins,withtheir lackoforderedstructure, represent attractive targets for the biophysical studies of the unfolded polypep-tidechainunderphysiological conditionsinvitro....

11p research12 29-04-2013 42 4   Download

Increasing evidence suggests that melatonin can exert some effect at nuclear level. Previous experiments using binding techniques clearly showed the existence of specificmelatonin binding sites in cell nucleus of rat liver. To further identify these sites, nuclear extracts fromrathepatocyteswere treated withdifferent percentages of ammoniumsulfate andpurified by affinity chromatography. Subsequent ligandblot analysis shows the presence of two polypeptides of
60 and
74 kDa that bind specifically to melatonin. ...

9p tumor12 20-04-2013 57 2   Download

Protein phosphatase 2A is a phosphoserine/threonine phosphatase implicated inmany cellular processes. The core enzyme comprises a catalytic and a PR65/A-subunit. The substrate specificity and subcellular localization are deter-mined by a third regulatory B-subunit (PR55/B, PR61/B¢ and PR72/130/B¢¢). To identify the proteins of the B¢¢family inXenopus laevisoocytes, aprophaseXenopusoocyte cDNA librarywas screened using humanPR130 cDNAas a probe. Three different classes of cDNAs were isolated....

12p tumor12 20-04-2013 28 3   Download

Human amylin (hA) is a small fibrillogenic protein that is the major con-stituent of pancreatic islet amyloid, which occurs in most subjects with type-2 diabetes mellitus (T2Dm). There is growing evidence that hA toxic-ity towards islet b-cells is responsible for their gradual loss of function in T2Dm. Preventing hA-mediated cytotoxicity has been proposed as a route to halt the progression of this disease, although this has not yet been dem-onstratedin vivo.

11p fptmusic 12-04-2013 30 1   Download

In the nematodeCaenorhabditis elegans, 40 genes code for astacin-likeproteins (nematodeastacins,NAS).The astacins are metalloproteases present in bacteria, invertebrates and vertebrates and serve avarietyof physiological functions like digestion, hatching, peptide processing, morphogenesis and pattern formation. With the exception of one distorted pseudogene, all the otherC. elegansastacins are expressed and are evidently functional. For 13 genes we found splicing patterns differing from the Genefinder predictions in WormBase, sometimes markedly....

12p fptmusic 12-04-2013 37 3   Download

Diatoms differ from higher plants by their antenna system, in terms of both polypeptide and pigment contents. A rapid isolation procedure was designed for the membrane-intrinsic light harvesting complexes (LHC) of the diatom Phaeodactylum tricornutumto establish whether different LHC subcomplexes exist, as well to determine an uneven distribution between them of pigments and polypeptides.

10p fptmusic 11-04-2013 47 3   Download

The aromatic hydrocarbon receptor (AhR)-dependent pathway involved in 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced immunotoxicity has been studied extensively, but the AhR-independent molecular mechan-ism has not. In previous studies we found that the AhR is not expressed in L-MAT, a human lymphoblastic T-cell line. In this report, we provide the following evidence that the protein kinase C (PKC)hactivity is func-tionally involved in the AhR-independent signal transduction mechanism that participates in the TCDD-induced L-MAT cell apoptosis....

13p awards 05-04-2013 29 2   Download

The unfolding process of the Blue Copper Protein (BCP) rusticyanin (Rc) has been studied using a wide variety of biochemical techniques. Fluorescence and CD spectroscop-ies reveal that the copper ion plays an essential role in sta-bilizing the protein and that the oxidized form is more efficient than the reducedspecies in this respect. Theaddition of guanidinium chloride to Rc samples produces aggrega-tion of the protein. Gel filtration chromatography and glutaraldehyde cross-linking experiments confirm the for-mation of such aggregates. ...

9p awards 05-04-2013 57 5   Download

Cytidine 5¢-triphosphate (CTP) synthase catalyses the ATP-dependent formation of CTP from uridine 5¢-triphosphate using either NH3orL-glutamine as the nitrogen source. The hydrolysis of glutamine is catalysed in the C-terminal glu-tamine amide transfer domain and the nascent NH3that is generated is transferred via an NH3 tunnel [Endrizzi, J.A., Kim, H., Anderson, P.M. & Baldwin, E.P. (2004) Biochemistry43, 6447–6463] to the active site of the N-ter-minal synthasedomainwhere theaminationreactionoccurs....

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The pulmonary surfactant prevents alveolar collapse and is required for normal pulmonary function. One of the important components of the surfactant besides phos-pholipids is surfactant-associated protein C (SP-C). SP-C shows complex oligomerization behavior and a transition to b-amyloid-like fibril structures, which are not yet fully understood. Besides this nonspecific oligomerization, MS and chemical cross-linking data combined with CD spectra provide evidence of a specific, mainlya-helical, dimer at lowto neutral pH....

7p dell39 03-04-2013 45 4   Download

Epstein–Barr virus (EBV) is a potent mitogenic and anti-apoptotic agent for B lymphocytes and is associated with several different types of human tumour. The abundantly expressed small viral RNA, EBER-1, binds to the growth inhibitory and pro-apoptotic protein kinase R (PKR) and blocks activation of the latter by double-stranded RNA. Recent evidence has suggested that expression of EBER-1 alone in EBV-negative B cells promotes a tumorigenic phe-notype and that this may be related to inhibition of the pro-apoptotic effects of PKR....

11p dell39 03-04-2013 41 3   Download

HIV gp41(24–157) unfolds cooperatively over the pH range of 1.0–4.0 withTmvalues of 100
C. At pH 2.8, protein unfolding was 80% reversible and theDHvH /DHcal ratio of 3.7 is indicative of gp41 being trimeric. No evidence for a monomer–trimer equilibrium in the concentration range of 0.3–36lMwas obtained by DSC and tryptophan fluores-cence. Glycosylation of gp41 was found to have only a marginal impact on the thermal stability. Reduction of the disulfide bond or mutation of both cysteine residues had only a marginal impact on protein stability. ...

14p dell39 03-04-2013 44 3   Download