A guide to ancient protein studies

Palaeoproteomics is an emerging neologism used to describe the application of mass spectrometry-based approaches to the study of ancient proteomes. As with palaeogenomics (the study of ancient DNA), it intersects evolutionary biology, archaeology and anthropology, with applications ranging from the phylogenetic reconstruction of extinct species to the investigation of past human diets and ancient diseases. However, there is no explicit consensus at present regarding standards for data reporting, data validation measures or the use of suitable contamination controls in ancient protein studies. Additionally, in contrast to the ancient DNA community, no consolidated guidelines have been proposed by which researchers, reviewers and editors can evaluate palaeoproteomics data, in part due to the novelty of the field. Here we present a series of precautions and standards for ancient protein research that can be implemented at each stage of analysis, from sample selection to data interpretation. These guidelines are not intended to impose a narrow or rigid list of authentication criteria, but rather to support good practices in the field and to ensure the generation of robust, reproducible results. As the field grows and methodologies change, so too will best practices. It is therefore essential that researchers continue to provide necessary details on how data were generated and authenticated so that the results can be independently and effectively evaluated. We hope that these proposed standards of practice will help to provide a firm foundation for the establishment of palaeoproteomics as a viable and powerful tool for archaeologists, anthropologists and evolutionary biologists

Molecular rearrangement of 9b-hydroxy-imidazo[4,5-c]quinoline-2,4-diones - an easy pathway to spiroindolinones

9b-Hydroxyimidazo[4,5-c]chinolin-2,4-diony se přesmykují v kyselém prostředí za vzniku tří odlišných spiroindolinonů v závislosti na typu substituce v poloze 3a.9b-Hydroxyimidazo[4,5-c]quinoline-2,4-diones rearrange in an acidic medium to give three different spiroindolinones depending on the type of substitution in position 3a

Metabolism of corticosterone in mammalian and avian intestine

11␤-hydroxysteroid dehydrogenase (11␤HSD) catalyzes the conversion of the glucocorticoids, corticosterone and cortisol, to the respective derivatives 11-dehydrocorticosterone and cortisone. The recent findings underline the importance of this enzyme in excluding glucocorticoids from mineralocorticoid receptors. In the present study, 11␤HSD activity was compared in the intestine of herbivorous (guinea pig), omnivorous (rat), and granivorous (hen) animals, i.e., in animals in which the Na ؉ transport either is or is not regulated by aldosterone under normal conditions and in which the plasma levels of individual glucocorticoids are different. Slices of various intestinal segments were incubated in the presence of corticosterone or 11-dehydrocorticosterone, and the steroids were extracted and analyzed by HPLC. In the mammalian intestine, the activity of 11␤HSD was very low (approaching zero) in aldosterone-insensitive segments (duodenum, jejunum) but significant activity was revealed in aldosterone-sensitive segments (ileum, cecum, and proximal and distal colon). In comparison with the rat, the guinea pig large intestine exhibited significantly higher activity of 11␤HSD. There was no detectable reductase activity (conversion of 11-dehydrocorticosterone to corticosterone) in any intestinal segments of either species. Unexpectedly, no 11␤HSD activity was observed in the avian intestine. It was found that, in contrast to the mammalian intestine, corticosterone was metabolized to 20-dihydrocorticosterone while 11-dehydrocorticosterone was converted to 11-dehydro-20-dihydrocorticosterone. The distribution of 20-hydroxysteroid dehydrogenase (20HSD) activity in the avian intestine was homogenous along the intestine and did not correlate with the mineralocorticoid sensitivity of intestinal segments. To trace different cosubstrate dependence of 11␤HSD and 20HSD, homogenates of ileum and distal colon were incubated with NAD ؉ /NADH or NADP ؉ / NADPH, respectively. In accordance with slice experiments mammalian intestine displayed only oxidation of corticosterone to 11-dehydrocorticosterone and NAD ؉ preference. In avian intestine, the metabolite formed from corticosterone was 11-dehydrocorticosterone in the presence of NAD ؉ or NADP ؉ whereas in the presence of NADPH 11-dehydro-20-dihydrocorticosterone and 20-dihydrocorticosterone were formed. Given the wide similarity between mineralocorticoid regulation of epithelial transport in mammals and birds, the unexpected finding of differences in the metabolism of corticosterone suggests that role of 20HSD is to allow aldosterone occupancy of mineralocorticoid receptors. 1998 Academic Press The enzyme 11␤-hydroxysteroid dehydrogenase (11␤HSD) interconverts active glucocorticoids (cortisol, corticosterone) to their 11-dehydro forms (cortisone, 11-dehydrocorticosterone), which normally exhibit very weak corticosteroid activity in vivo. There is now considerable evidence suggesting that 11␤HSD decreases the concentration of intracellular glucocorticoids to levels that allow aldosterone to occupy nonselective mineralocorticoid receptor

Separation of poly(amidoamine) (PAMAM) dendrimer generations by dynamic coating capillary electrophoresis

The separation of compounds possessing amino groups (peptides, proteins, polyamino compounds) by capillary zone electrophoresis suffers from the interaction (sticking) of these solutes with the capillary wall. This sticking can result in the absence or incomplete separation of compounds or even in their retention in the capillary. Polyamidoamine (PAMAM) dendrimers are a class of spherical polymers with primary amino groups at the surface. These compounds can be separated reasonably well at acidic pH but not at neutral pH. A new method based on the dynamic coating of the capillary was developed for the separation of these compounds at pH 7.4. The method comprises separation in a fused-silica capillary (57 cm total length, 50 cm to the detector, ID 75 microm) and a background electrolyte consisting of a Tris-phosphate buffer (50 mmol/L, pH 7.4) and 0.05% (w/v) polyethyleneimine. This system is suitable for the separation of 7 generations of dendrimers (generations 0-6). The dynamic coating agent (polyethyleneimine) also improves the separation at acid pH.info:eu-repo/semantics/publishedVersio

Molecular rearrangement of 9b-hydroxy-imidazo[4,5-c]quinoline-2,4-diones ? a convenient pathway to spiro imidazolidine oxindole derivatives

3-Alkyl/Aryl-3-aminochinolin-2,4-diony reagují s isokyanáty na nové titulní sloučeniny. Tyto přesmykují varem v kyselém prostředí a poskytují tři odlišné typy spiro-oxindolů.3-Alkyl/Aryl-3-aminoquinoline-2,4-diones react with isocyanates to give novel title compounds. These compounds rearrange by boiling in acidic environment to give three different type of spiro-oxindoles

Reaction of 3-phenyl-3-aminoquinoline-2,4-diones with isothiocyanates. Facile access to novel spiro-linked 2-thioxoimidazolidine-oxindoles and imidazoline-2-thiones

3-Amino-1H,3H-chinolin-2,4-diony reagují s thiomočovinou nebo thiokyanatanem draselným ve vroucí kyselině octové za vzniku nových 2,3-dihydro-3-thioxoimidazo[1,5-c]chinazolin-5(6H)-onů nevysokých výtěžcích. Avšak, jestliže jsou výchozí látky substituovány benzylovou skupinou v poloze 3, proběhne C-debenzylace za vzniku 2,3-dihydro-2-thioxo-1H-imidazo[4,5-c]chinolin-4(5H)-onů. Podle navrženého reakčního mechanismu proběhne molekulární přesmyk původně vytvořených monosubstituovaných močovin. Všechny sloučeniny byly charakterizovány pomocí 1H, 13C, a 15N NMR, a IR spektroskopií stejně jako hmotovými spektry.3-Phenyl-3-amino-1H,3H-quinoline-2,4-diones (1) react with alkyl or aryl isothiocyanates to give novel 9b-hydroxy-3a-phenyl-1,2,3,3a-tetrahydro-2-thioxo-5H-imidazo[4,5-c]quinolin-4(9bH)-ones in high yields. These compounds rearrange in boiling acetic acid or concentrated hydrochloric acid to give novel 5-phenyl-2-thioxospiro[4H-imidazol-4,3´-[3H]indol]-2´(1´H,3H)-ones, 5-hydroxy-5-phenyl-2-thioxospiro[imidazolidine-4,3´-[3H]indol]-2´-ones, and (2-methylaminophenyl)-5-phenyl-1H-imidazole-2(3H)-thiones. All compounds were characterized by their 1H, 13C, IR and MS data, and in some cases also by 15N NMR data. The structures and compositions of four compounds were confirmed by single crystal X-ray diffraction

Synthesis of 2-thioxo-imidazolines via reaction of 1-unsubstituted 3-aminoquinoline-2,4-diones with isothiocyanates

3-Alkyl/Aryl-3-aminochinoline-2,4-diony reagují s isothiokyanáty za tvorby 3a-alkyl/aryl-1,2,3,3a-tetrahydro-9b-hydroxy-2-thioxo-5H-imidazo-[4,5-c]chinolin-4(9bH)-onů. Tyto sloučeniny přesmykují v kyselém prostředí na nové 4-(2-aminofenyl)-1H-imidazol-2(3H)-thiony a 1,3-bis(2-(2,3-dihydro-2-thioxo-1H-imidazol-5-yl)fenyl)močoviny.3-Alkyl/Aryl-3-aminoquinoline-2,4-diones react with isothiocyanates to give 3a-alkyl/aryl-1,2,3,3a-tetrahydro-9b-hydroxy-2-thioxo-5H-imidazo-[4,5-c]quinolin-4(9bH)-ones. These compounds rearrange in an acidit environment to give novel 4-(2-aminophenyl)-1H-imidazole-2(3H)-thiones and 1,3-bis(2-(2,3-dihydro-2-thioxo-1H-imidazol-5-yl)phenyl)ureas

Reaction of 1-substituted 3-aminoquinoline-2,4-diones with isothiocyanates. An easy pathway to generate novel 2-thioxo-10H-spiro[imidazoline-5,3-indole]-2,2´-diones.

3-Butyl-3-aminochinolin-2,4-diony reagují s isothiokyanáty za tvorby nových 3a-butyl-9b-hydroxy-hexahydro-imidazo[4,5-c]chinolin-2-onů. Tyto sloučeniny přesmykují v kyselém prostředí a poskytují (E)- a/nebo (Z)-4-butyliden-2-thioxo-1´H-spiro[imidazolin-5,3´-indol]-2,2-diony.3-Butyl-3-aminoquinoline-2,4-diones react with isothiocyanates to give novel 3a-butyl-9b-hydroxy-hexahydro-imidazo[4,5-c]quinolin-2-ones . These compounds rearrange in an acidit environment to give (E)- and/or (Z)-4-butylidene-2-thioxo-1´H-spiro[imidazoline-5,3´-indole]-2,2-diones