Structure identification of the complex-type,asparagine-linked sugar chains of β-d-galactosyl-transferase purified from human milk

The asparagine-linked sugar chains of human milk galactosyltansferase were quantitatively released as oligosaccharides from the polypeptide backbone by hydrazinolysis. They were converted into radioactive oligosaccharides by sodium borotritiate reduction after N-acetylation, and fractionated by paper electrophoresis and by Bio-Gel P-4 column chromatography after sialidase treatment. Structural studies of each oligosaccharides by sequential exoglycosidase digestion and methylation analysis indicated that the galactosyltransferase contains bi, tri-, and probably tetra-antennary, complex-type oligosaccharides having α-d-Manp-(1→3)-[α-d-Manp-(1→6)]-β-d-Manp-(1→4)-β-d-GlcpNAc-(1→4)-α-d-[Fucp-(1→6)]-d- GlcNAc as their common core. Variation is produced by the different locations and numbers of the five different outer chains: β-d-Galp-(1→4)-d-GlcNAc, α-l-Fucp-(1→3)-[β-d-Galp-(1→4)]-d-GlcNAc, α-NeuAc-(2→6)-β-d-Galp-(1→4)-d-GlcNAc, α-l-Fucp-(1→3)-[β-d-Galp-(1→4)]-β-d-GlcpNAc-(1→3)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)]-d- GlcNAc, and α-NeuAc-(2→6)-β-d-Galp-(1→4)-β-d-GlcpNAc-(1→3)-β-d-Galp-(1→4)-[α-l-Fucp-(1→3)-β-d-GlcNAc.     

The carbohydrate units of ovalbumin: Complete structures of three glycopeptides

Three glycopeptides, obtained in quantity from ovalbumin by exhaustive digestion with Pronase and purified by ion-exchange chromatography and gel filtration, had mannose-2-acetamido-2-deoxyglucose-aspartic acid ratios of 5:4:1, 6:2:1, and 5:2:1. The structures of the glycopeptides have been investigated by sequential digestion with purified exo-glycosidases, Smith degradation, and selective acetolysis, and by methylation analysis of the glycopeptides and their degradation products. The resulting data indicated the structures to be α-d-Manp-(1→6)-[α-d- Manp-(1→3)]-α-d-Manp-(1→6)-[β-d-GlcNAcp-(1→4)]-[β-d-GlcNAcp-(1→2)-α-d- Manp-(1→3)]-β-d-Manp-(1→4)-β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn, α-d- Manp-(1→6)-[α-d-Manp-(1→3)]-α-d-Manp-(1→6)-[α-d-Manp-(1→2)-α-d-Manp- (1→3)]-β-d-Manp-(1→4)-β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn, and α-d-Manp- (1→6)-[α-d-Manp-(1→3)]-α-d-Manp-(1→6)-[α-d-Manp-(1→3)]-β-d-Manp-(1→4)- β-d-GlcNAcp-(1→4)-β-d-GlcNAcp→Asn. The glycopeptides had a common-core structure consisting of five mannose and two hexosamine residues, but the two larger glycopeptides were not homologous.     

Interaction specificity of Arabidopsis 14-3-3 proteins with phototropin receptor kinases

Phototropin receptor kinases play an important role in optimising plant growth in response to blue light. Much is known regarding their photochemical reactivity, yet little progress has been made to identify downstream signalling components. Here, we isolated several interacting proteins for Arabidopsis phototropin 1 (phot1) by yeast two-hybrid screening. These include members of the NPH3/RPT2 (NRL) protein family, proteins associated with vesicle trafficking, and the 14-3-3 lambda (λ) isoform from Arabidopsis. 14-3-3λ and phot1 were found to colocalise and interact in vivo. Moreover, 14-3-3 binding to phot1 was limited to non-epsilon 14-3-3 isoforms and was dependent on key sites of receptor autophosphorylation. No 14-3-3 binding was detected for Arabidopsis phot2, suggesting that 14-3-3 proteins are specific to phot1 signalling.

Structured summary

MINT-7146953: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF7 (uniprotkb:Q9LFJ7) by two hybrid (MI:0018)MINT-7147335: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 phi (uniprotkb:P46077) by far Western blotting (MI:0047)MINT-7146854: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with RPT2 (uniprotkb:Q682S0) by two hybrid (MI:0018)MINT-7147215: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by anti tag coimmunoprecipitation (MI:0007)MINT-7147044, MINT-7147185, MINT-7147200, MINT-7147413: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 lambda (uniprotkb:P48349) by far Western blotting (MI:0047)MINT-7146983: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with 14-3-3 lambda (uniprotkb:P48349) by two hybrid (MI:0018)MINT-7146871: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with NPH3-like (uniprotkb:Q9S9Q9) by two hybrid (MI:0018)MINT-7146905: PHOT1 (uniprotkb:O48963) physically interacts (MI:0915) with ARF2 (uniprotkb:Q9M1P5) by two hybrid (MI:0018)MINT-7147364: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 upsilon (uniprotkb:P42645) by far Western blotting (MI:0047)MINT-7147234: PHOT1 (uniprotkb:O48963) physically interacts (MI:0914) with 14-3-3 kappa (uniprotkb:P48348) by far Western blotting (MI:0047)     

Evidence for leptin receptor isoforms heteromerization at the cell surface

Leptin mediates its metabolic effects through several leptin receptor (LEP-R) isoforms. In humans, long (LEPRb) and short (LEPRa,c,d) isoforms are generated by alternative splicing. Most of leptin’s effects are believed to be mediated by the OB-Rb isoform. However, the role of short LEPR isoforms and the possible existence of heteromers between different isoforms are poorly understood. Using BRET1 and optimized co-immunoprecipitation, we observed LEPRa/b and LEPRb/c heteromers located at the plasma membrane and stabilized by leptin. Given the widespread coexpression of LEPRa and LEPRb, our results suggest that LEPRa/b heteromers may represent a major receptor species in most tissues.

Structured summary

MINT-7714817: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRb (uniprotkb:P48357-1) by anti tag co-immunoprecipitation (MI:0007)MINT-7714785: LEPRc (uniprotkb:P48357-2) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by bioluminescence resonance energy transfer (MI:0012)MINT-7714951, MINT-7714744: LEPRa (uniprotkb:P48357-3) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by bioluminescence resonance energy transfer (MI:0012)MINT-7714859: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by anti tag co-immunoprecipitation (MI:0007)MINT-7714885, MINT-7714672: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRb (uniprotkb:P48357-1) by bioluminescence resonance energy transfer (MI:0012)MINT-7714835: LEPRa (uniprotkb:P48357-3) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by anti tag co-immunoprecipitation (MI:0007)MINT-7714914, MINT-7714723, MINT-7714759: LeprB (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRa (uniprotkb:P48357-3) by bioluminescence resonance energy transfer (MI:0012)MINT-7714703, MINT-7714936, MINT-7714772: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by bioluminescence resonance energy transfer (MI:0012)MINT-7714872: LEPRb (uniprotkb:P48357-1) physically interacts (MI:0915) with LEPRc (uniprotkb:P48357-2) by anti tag co-immunoprecipitation (MI:0007)     

Synthesis of two purple-membrane glycolipids and the glycolipid sulfate O-(β-d-glucopyranosyl 3-sulfate)-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2, 3-di-O-phytanyl-sn-glycerol

The two purple-membrane glycolipids O-β-d-glucopyranosyl- and O-β-d-galactopyranosyl-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2, 3-di-O-phytanyl-sn-glycerol were prepared by coupling O-(2,3,4-tri-O-acetyl-α-d-mannopyranosyl)-(1→2)-O-(3,4,6-tri-O-acetyl-α-d-glucopyranosyl)-(1→1)-2, 3-di-O-phytanyl-sn-glycerol (9) with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide or 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide, respectively, followed by deacetylation. The glycolipid sulfate O-(β-d-glucopyranosyl 3-sulfate)-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2,3-di-O-phytanyl-sn-glycerol was prepared by coupling of 9 with 2,4,6-tri-O-acetyl-3-O-trichloroethyloxycarbonyl-α-d-glucopyranosyl bromide in the presence of Hg(CN)₂/HgBr₂ followed by selective removal of the 3?-trichloroethyloxycarbonyl group, sulfation of HO-3?, and deacetylation. The suitably protected key-intermediate 9 could be prepared by two distinct approaches.     

Acylated cyanidin 3-sambubioside-5-glucosides from the purple-violet flowers of Matthiola longipetala subsp. bicornis (Sm) P. W. Ball. (Brassicaceae)

A novel acylated cyanidin 3-sambubioside-5-glucoside was isolated from the purple-violet flowers of Matthiola longipetala subsp. bicornis (Sm) P. W. Ball. (family: Brassicaceae), and determined to be cyanidin 3-O-[2-O-(2-O-(trans-feruloyl)-β-xylopyranosyl)-6-O-(trans-feruloyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside] by chemical and spectroscopic methods. In addition, two known acylated cyanidin 3-sambubioside-5-glucosides, cyanidin 3-O-[2-O-(2-O-(trans-sinapoyl)-β-xylopyranosyl)-6-O-(trans-feruloyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside] and cyanidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(trans-feruloyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside] were identified in the flowers.     

Synthesis of phenyl O-α-l-fucopyranosyl-(1→2)-O-β-d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-α-d-galactopyranoside

phenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-3-O-[4,6-O-(p-methoxybenzylidene)-β-d-alactopyranosyl]-α-d-galactopyranoside (3) was prepared from phenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-3-O-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl)-α-d-galactopyranoside by zemplén deacetylation, followed by reaction with p-methoxybenzaldehyde in the presence of anhydrous zinc chloride. The selective benzoylation of 3 gave the 3′-benzoate which, on condensation with 2,3,4-tri-O-benzyl-α- l-fucopyranosyl bromide under catalysis by halide ion, afforded a crystalline trisaccharide from which the title trisaccharide was obtained by debenzoylation followed by catalytic hydrogenolysis.     

Two-dimensional, 1H-n.m.r. study of peracetylated, reduced derivatives of three oligosaccharides isolated from human milk

The structures of the peracetylated derivatives of the following alditols obtained from oligosaccharides of human milk have been established by two-dimensional, J-resolved and J-correlated, ¹H-n.m.r. spectroscopy at 360 MHz: β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-β- d-Galp-(1→4)- d-Glc-ol, α- l-Fucp-(1→2)-β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-β- d-Galp-(1→4)- d-Glc-ol, and β- d-Galp-(1→3)-β- d-GlcpNAc-(1→3)-[β- d-Galp-(1→4)-β- d-GlcpNAc-(1→6)]-β- d-Galp-(1→4)- d-Glc-ol.     

Quantitative methods for determining the points of O-(carboxymethyl) substitution in O-(carboxymethyl)-guar

Two methods are described for locating the O-(carboxymethyl) groups in O-(carboxymethyl)guar. In Method I, O-(carboxymethyl)guar was depolymerized by methanolysis, the O-(carboxymethyl) groups were reduced, and the mixture of methyl glycosides and O-(2-hydroxyethyl)-substituted methyl glycosides was converted into a mixture of per-O-acetylated alditols and partially O-(2-acetoxyethyl)ated, partially O-acetylated alditols. Analysis of these alditols by gas-liquid chromatography-mass spectrometry allowed the positions of substitution of the O-(carboxymethyl) groups on the galactosyl groups and mannosyl residues to be determined. However, this method did not distinguish between O-(carboxymethyl) substitution on 4-linked and 4,6-linked mannosyl residues. This limitation was overcome by the more-detailed analysis provided by Method II, in which O-(carboxymethyl)guar was carboxyl-reduced, the product methylated, the glycosyl residues hydrolyzed, the sugars reduced, and the alditols acetylated to yield a mixture of partially O-acetylated, partially O-methylated alditols and partially O-acetylated, partially O-(2-methoxyethyl)ated, partially O-methylated alditols. These derivatives, when separated and quantitated by g.l.c., and identified by g.l.c.-m.s., gave a quantitative measure of every type of carboxymethyl substitution in guar.     

A tetra-acylated cyanidin 3-sophoroside-5-glucoside from the purple-violet flowers of Moricandia arvensis (L.) DC. (Brassicaceae)

A novel tetra-acylated cyanidin 3-sophoroside-5-glucoside was isolated from the purple-violet flowers of Moricandia arvensis (L.) DC. (Family: Brassicaceae), and determined to be cyanidin 3-O-[2-O-(2-O-(4-O-(6-O-(4-O-(β-glucopyranosyl)-trans-caffeoyl)-β-glucopyranosyl)-trans-caffeoyl)-β-glucopyranosyl)-6-O-(trans-caffeoyl)-β-glucopyranoside]-5-O-[6-O-(malonyl)-β-glucopyranoside] by chemical and spectroscopic methods.     

Synthesis of the tetrasaccharide repeating-unit of the O-specific polysaccharide from Salmonella senftenberg

The oligosaccharide β-d-Man-(1 → 4)-α-l-Rha (1 → 3)-d-Gal-(6 ← 1)-α-d-Glc, which is the repeating unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella senftenberg, was obtained by glycosylation of benzyl 2,4-di-O-benzyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside or benzyl 2-O-acetyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside with 3-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-β-l-rhamnopyranose 1,2-(methyl orthoacetate) followed by removal of protecting groups.     

Synthesis of the repeating units of Schizophyllan

The tetrasaccharides β-d-Glcp-(1→3)-β-d-Glcp-(1→3)-[β-d-Glcp-(1→6)]-d-Glcp, β-d-Glcp-(1→3)-[β-d-Glcp-(1→6)]-β-d-Glcp-(1→3)-d-Glcp, and β-d-Glcp-(1→6)-β-d-Glcp-(1→3)-β-d-Glcp-(1→3)-d-Glcp, corresponding to the three possible repeating-units of Schizophyllan, have been synthesised by silver trifluoromethanesulfonate-promoted Koenigs-Knorr type condensations, using 2,4,6-tri-O-acetyl-3-O-allyl-α-d-glucopyranosyl bromide as the key intermediate.     

Isolation and synthesis of trans- and cis-(−)-clovamides and their deoxy analogues from the bark of Dalbergia melanoxylon

N-(3′,4′-Dihydroxy-trans-cinnamoyl)-3-(3,4-dihydroxyphenyl)-L-alanine [(?)-clovamide], the major phenolic metabolite (0.1%) in the bark of Dalbergia melanoxylon, is associated with minor proportions of its cis-isomer, and similar pairs of geometrical isomers of their deoxy analogues N-(4′-hydroxycinnamoyl)-3-(3,4-dihydroxyphenyl)-L-alanine and N-(4′-hydroxycinnamoyl)-3-(4-hydroxyphenyl)-L-alanine. (?)-Trans-clovamide is synthesized by direct condensation of the acid chloride of caffeic acid with L-DOPA. Diagnostic CD spectra of these compounds and ¹³C spectra of (?)-trans- and (?)-cis-clovamides are recorded.     

Synthesis of 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine)-d-glucopyranoses

Five 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine)-d-glucopyranoses (lipophilic, muramoyl dipeptide analogs) were synthesized from benzyl 2-(benzyloxycarbonylamino)-3-O-(d-1-carboxyethyl)-2-deoxy-5,6-O-isopropylidene-β-dglucopyranoside (1). Methanesulfonylation of 3, derived from the methyl ester of 1 by O-deisopropylidenation, gave the 6-methanesulfonate (4). (Tetrahydropyran-2-yl)ation of 4 gave benzyl 2-(benzyloxycarbonylamino)-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-6-O-(methylsulfonyl)-5-O-(tetrahydropyran-2-yl)-β-d- glucofuranoside, which was treated with sodium azide to give the corresponding 6-azido derivative (6). Condensation of benzyl 6-amino-2-(benzyloxycarbonyl-amino)-2,6-dideoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-5-O-(tetrahydropyran-2-yl)-β-d-glucofuranoside, derived from 6 by reduction, with the activated esters of octanoic, hexadecanoic, and eicosanoic acid gave the corresponding 6-N-fatty acyl derivatives (8–10). Coupling of the 2-amino derivatives, obtained from compounds 8, 9, and 10 by catalytic reduction, with the activated esters of the fatty acids, gave the 2,6-(diacylamino)-2,6-dideoxy derivatives (11–15). Condensation of the acids, formed from 11–15 by de-esterification, with the benzyl ester of l-alanyl-d-isoglutamine, and subsequent hydrolysis, afforded benzyl 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine benzyl ester)-β-d-glucofuranosides. Hydrogenation of the dipeptide derivatives thus obtained gave the five lipophilic analogs of 6-amino-6-deoxymuramoyl dipeptide, respectively, in good yields.     

Novel O-antigen of Hafnia alvei PCM 1195 lipopolysaccharide with a teichoic acid-like structure

The lipopolysaccharide (LPS) of Hafnia alvei strain PCM 1195 was obtained by the hot phenol/water method. The O-specific polysaccharide was released by mild acidic hydrolysis and isolated by gel filtration. The structure of the O-specific polysaccharide was investigated by ¹H, ¹³C, and ³¹P NMR spectroscopy, MALDI-TOF MS, and GC-MS, accompanied by monosaccharide and methylation analysis. It was concluded that the O-specific polysaccharide is composed of a hexasaccharide repeating units interlinked with a phosphate group: {→4-α-d-Glcp-(1→3)-α-l-FucpNAc-(1→3)-[α-d-Glcp-(1→4)]-α-d-GlcpNAc-(1→3)-α-l-FucpNAc-(1→4)-α-d-Glcp-(1→P}_n.     

Cooperative aspects of hydrogen bonding in carbohydrates

Various compounds related to the antibacterial, sulfanilamide drugs have been prepared from dehydro-l-ascorbic acid or its d-erythro analog by reaction with hydrazines related to sulfanilamide, sulfadiazine, sulfamerazine, sulfamethazine, and sulfamethoxydiazine, whereby the 2-mono- and 2,3-bis-(hydrazone) were isolated. After opening of the lactone ring in the bis(hydrazones) with alkali, nucleophilic attack, on the carbonyl group, of the imino nitrogen atom of the 3-hydrazone residue afforded 3-(l-threo-glycerol-1-yl)-1-phenyl- and -1-(p-sulfamylphenyl)-4,5-pyrazole-dione 4-(p-sulfamylphenlhydrazone) and the related 3-(d-erythro-glycerol-1-yl)compounds. Whereas acetylation of l-threo-2,3-hexodiulosono-1,4-lactone 2,3-bis(p-sulfamylphenylhydrazone) (9) and 3-(l-threo-glycerol-1-yl)-1-(p-sulfamylphenyl)-4,5-pyrazoledione 4-(p-sulfamylphenylhydrazone) (15) gave the O-acetyl derivatives, benzoylation of 15 gave the di-N-benzoy ltri-O-benzoyl compound. Reaction of 9 with cupric chloride gave 3,6-anhydro-3-(p-suIfamylphenylazo) -l-xylo-2-hexulosono-1,4-lactone 2-(p-sulfamylphenylhydrazone). The 3-(l-threo-glycerol-1-yl)-1-(p-sulfamylphenyl)flavazole (35) was prepared by the rearrangement of 3-[(1-p-sulfamylphenyl)hydrazono-l-threo-trihydroxybutyl]-2-quinoxalinont (33). Periodate oxidation of 15,33, and 35 gave 3-formyl-1-(p-sulfamylphenyl)-4,5-pyrazoledione 4-(p-sulfamylphenylhydrazone), 3-1-[(p-sulfamylphenyl)hydrazono]glyoxal-1-yl]-2-quinoxalinone, and 3-formyl-1-(p-sulfamylphenyl)flavazole, respectively. The i.r. and n.m.r. spectral data for some of these derivatives are reported.     

Synthesis of some C-glycosyl- and polyhydroxyalkyl-pyridazines

Photo-oxygenation of 3-hydroxymethyl-5-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-2-methylfuran, 5-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-3-(1-hydroxyethyl)-2-methylfuran (8a), and 2-methyl-5-(1,2,3,4-tetra-O-acetyl-d-arabino-tetritol-1-yl)-3-furoic acid (8b) yielded the corresponding endo-peroxides, which were transformed into 4-hydroxymethyl-6-(2,3-O-isopropylidene-β-d-erythrofuranosyl)-3-methylpyridazine, 6-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-4-(1-hydroxyethyl)-3-methylpyridazine, and 6-(d-arabino-tetritol-1-yl)-3-methylpyridazine by treatment with hydrazine. The γ-di-ketones (Z)-1-(1,2:3,4-di-O-isopropylidene-d-arabino-tetritol-1-yl)-3-(1-hydroxyethyl)pent-2-ene-1,4-dione and d-arabino-6,7,8,9-tetraacetoxy-4-methoxynonane-2,5-dione can be obtained by reduction of the endo-peroxides 9a and 9b (derived from 8a and 8b, respectively) with dimethyl sulphide. The C → O rearrangement reported for C-glycosyl endo-peroxides was also observed for 9a.     

Phosphorylation of more than one site is required for tight interaction of human tau protein with 14-3-3ζ

Serine residues phosphorylated by protein kinase A (PKA) in the shortest isoform of human tau protein (τ3) were sequentially replaced by alanine and interaction of phosphorylated τ3 and its mutants with 14-3-3 was investigated. Mutation S156A slightly decreased interaction of phosphorylated τ3 with 14-3-3. Double mutations S156A/S267A and especially S156A/S235A, strongly inhibited interaction of phosphorylated τ3 with 14-3-3. Thus, two sites located in the Pro-rich region and in the pseudo repeats of τ3 are involved in phosphorylation-dependent interaction of τ3 with 14-3-3. The state of τ3 phosphorylation affects the mode of 14-3-3 binding and by this means might modify tau filament formation.

Structured summary

MINT-7233358, MINT-7233372, MINT-7233384: 14-3-3 zeta (uniprotkb:P63104) and Tau 3 (uniprotkb:P10636-3) bind (MI:0407) by molecular sieving (MI:0071)MINT-7233323, MINT-7233334, MINT-7233346: Tau 3 (uniprotkb:P10636-3) and 14-3-3 zeta (uniprotkb:P63104) bind (MI:0407) by crosslinking studies (MI:0030)MINT-7233285, MINT-7233297, MINT-7233310: 14-3-3 zeta (uniprotkb:P63104) and Tau 3 (uniprotkb:P10636-3) bind (MI:0407) by comigration in non-denaturing gel electrophoresis (MI:0404)     

Synthesis of a branched d-mannopentaoside and a branched d-mannohexaoside: Models of the outer chain of the glycan of soybean agglutinin

Synthetic routes are described to the d-mannopentaoside methyl 3-O-(3,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-6-O-α-d-mannopyranosyl-α-d-mannopyranoside, and the d-mannohexaoside methyl 3-O-(3,6-di-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-6-O-(2-O-α-d-mannopyranosyl-α-d-mannopyranosyl)-α- d-mannopyranoside, formed in a regio- and stereo-controlled way by employing the properly protected d-mannobioside methyl 2,4-di-O-benzyl-3-O-(2,4-di-O-benzyl-α-d-mannopyranosyl)-α-d-mannopyranoside and d-mannotrioside methyl 2,4-di-O-benzyl-3-O-(2,4-di-O-benzyl-α-d-mannopyranosyl)-6-O-(3,4,6-tri-O-benzyl-α-d- mannopyranosyl)-α-d-mannopyranoside as key intermediates.     

Arvensoside A and B,triterpenoid saponins from Calendula arvensis

Two new triterpenoid glycosides from the aerial parts of Calendula arvensis were identified as oleanolic acid-28-O-β-D-glucopyranoside-3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) and oleanolic acid 3-β-O-(O-β-D-galactopyranosyl(1 → 3)-β-D-glucopyranoside) by FAB, FAB MIKE mass spectrometry and ¹³C NMR spectroscopy.