Synthesis of Galβ1-4GlcNAcβ- and Galβ1-3GalNAcα-O-L-serine Derivatives employing glycosidases

A new approach for the highly specific preparation of L-serine conjugates of lactosamine and Gal1-3GalNAc is described. Thus, the L-serine derivative of lactosamine Gal1-4GlcNAc-O-(N-Z)-Ser-OEt, was obtained from lactose, employing GlcNAc-O-(N-Z)-Ser-OEt as acceptor and a yeast -galactosidase as catalyst Galp 1-3GalNAc-O-(N-Alloc)-Ser-OMe was obtained from lactose, employing GalNAc-O-(N-Alloc)-Ser-OMe as acceptor and -galactosidase from bovine testes as catalyst.     

ProcessingO-glycan core 1, Galβ1-3GalNAcα-R. Specificities of core 2, UDP-GlcNAc: Galβ1-3GalNAc-R(GlcNAc to GalNAc) β6-N-acetylglucosaminyltransferase and CMP-sialic acid:Galβ1-3GalNAc-R α3-sialyltransferase

To elucidate control mechanisms ofO-glycan biosynthesis in leukemia and to develop biosynthetic inhibitors we have characterized core 2 UDP-GlcNAc:Gal1-3GalNAc-R(GlcNAc to GalNAc) 6-N-acetylglucosaminyl-transferase (EC 2.4.1.102; core 2 6-GlcNAc-T) and CMP-sialic acid: Gal1-3GalNAc-R 3-sialyltransferase (EC 2.4.99.4; 3-SA-T), two enzymes that are significantly increased in patients with chronic myelogenous leukemia (CML) and acute myeloid leukemia (AML). We observed distinct tissue-specific kinetic differences for the core 2 6-GlcNAc-T activity; core 2 6-GlcNAc-T from mucin secreting tissue (named core 2 6-GlcNAc-T M) is accompanied by activities that synthesize core 4 [GlcNAc1-6(GlcNAc1-3)GalNAc-R] and blood group I [GlcNAc1-6(GlcNAc1-3)Gal-R] branches; core 2 6-GlcNAc-T in leukemic cells (named core 2 -GlcNAc-T L) is not accompanied by these two activities and has a more restricted specificity. Core 2 6-GlcNAc-T M and L both have an absolute requirement for the 4- and 6-hydroxyls ofN-acetylgalactosamine and the 6-hydroxyl of galactose of the Gal1-3GalNAc-benzyl substrate but the recognition of other substituents of the sugar rings varies, depending on the tissue. 3-sialytransferase from human placenta and from AML cells also showed distinct specificity differences, although the enzymes from both tissues have an absolute requirement for the 3-hydroxyl of the galactose residue of Gal1-3GalNAc-Bn. Gal1-3(6-deoxy)GalNAc-Bn and 3-deoxy-Gal1-3GalNAc-Bn competitively inhibited core 2 6-GlcNAc-T and 3-sialyltransferase activities, respectively.Abbreviations AFGP antifreeze glycoprotein - AML acute myeloid leukemia - Bn benzyl - CML chronic myelogenous leukemia - Fuc l-fucose - Gal, G d-galactose - GalNAc, GA N-acetyl-d-galactosamine - GlcNAc, Gn N-acetyl-d-glucosamine - HC human colonic homogenate - HO hen oviduct microsomes - HPLC high performance liquid chromatography - mco 8-methoxycarbonyl-octy - Me methyl - MES 2-(N-morpholino)ethanesulfonate - MK mouse kidney homogenate - onp o-nitrophenyl - PG pig gastric mucosal microsomes - pnp p-nitrophenyl - RC rat colonic mucosal microsomes - SA sialic acid - T transferase Enzymes: UDP-GlcNAc:Gal1-3GalNAc-R (GlcNAc to GalNAc) 6-N-acetylglucosaminyltransferase,O-glycan core 2 6-GlcNAc-transferase, EC 2.4.1.102; CMP-sialic acid: Gal1-3GalNAc-R 3-sialyltransferase,O-glycan 3-sialic acid-transferase, EC 2.4.99.4.     

Presence of natural anti-Galα1-4GalNAcβ1-3Gal (anti-NOR) antibodies in animal sera

Rare polyagglutinable NOR erythrocytes contain unusual globoside extention products terminating with a Galα1-4GalNAcβ1-3Gal- unit. This trisaccharide epitope is recognized by recently characterized antibodies naturally occurring in most human sera (Duk et al., Glycobiology, 15, 109, 2005). These antibodies represent two major types of fine specificity. All these antibodies are most strongly inhibited by Galα1-4GalNAcβ1-3Gal (NOR-tri), and weakly by Galα1-4Gal. However, the type 1 antibodies are strongly inhibited by Galα1-4Galβ1-3Gal-R and weakly by Galα1-4GalNAc, while the type 2 antibodies show the opposite reactivities with these two oligosaccharides. Similar antibodies have now been found in horse, rabbit and pig sera. The antibodies were purified from animal sera by affinity chromatography on Galα1-4GalNAcβ1-3Gal-human serum albumin(HSA)-Sepharose 4B conjugate. The specificity of the antibodies was determined by binding to ELISA plates coated with several α-galactosylated oligosaccharide-polyacrylamide (PAA) or -HSA conjugates and by inhibition with synthetic oligosaccharides. The purified antibodies bound specifically to conjugates containing NOR-tri. The inhibition of binding showed that the animal sera also contain two types of anti-NOR antibodies: type 2 was found in the horse serum, and a mixture of both types was present in rabbit and pig serum. These results indicate that anti-NOR, a new and distinct kind of anti-αGal antibody, are present in animal sera and show similar specificties and diversity as their counterparts found in human sera.     

Concanavalin A-stimulated expression of gangliosides with GalNAcβ1-4(NeuAcα2-3)Galβ structure in murine thymocytes

We analysed the glycolipids of mouse thymocytes before and after Concanavalin A (Con A) or recombinant interleukin-2 (rIL-2) stimulation by TLC-immunostaining with carbohydrate-specific antiglycolipid antibodies. The thymocytes were cultured in serum-free medium in the presence of 500 ng ml^–1 Con A, 10 U ml^–1 rIL-2 or Con A plus rIL-2 for 6, 12, 24, 48, and 72 h, and were found to start proliferating 24 h after cultivation in the presence of Con A or Con A plus rIL-2, the maximum levels being reached at 72 h and 48 h, respectively, in a thymidine uptake experiment. The concentrations of II³Neu-Gg₄Cer, Gg₄Cer and IV³GalNAc-Gb₄Cer after 48 h Con A stimulation were found to be at almost the original levels. Conversely, II³Neu-Gg₃Cer, which was not detected in the thymocytes at the start, began to appear after 48 h stimulation with Con A and Con A plus rIL-2, and IV³Neu-Gg₅Cer in the cells 48 h after stimulation with Con A and Con A plus rIL-2 has increased to 41 and 44 times higher than in the original cells, respectively, as judged on TLC-immunostaining with monoclonal antibody YHD-06, which detects the GalNAc1-4(NeuAc or NeuGc2-3)Gal-structure. These results indicate that the increased synthesis of both gangliosides, in other words, the activation ofN-acetylgalactosaminyltransferase, is associated with the mitogen-induced proliferation.N-Acetylneuraminic acid was the sole sialic acid in II³Neu-Gg₃Cer which newly appeared in the cells on stimulation, whereas the sialic acid of IV³Neu-Gg₅Cer was a mixture ofN-acetyl- andN-glycoloylneuraminic acids. This result may suggest that the substrates for the two differentN-acetylgalactosaminyltransferases must be different. This GalNAc1-4(NeuAc or NeuGc2-3)Gal-structure was also detected on the surface of the Con A or Con A plus rIL-2 stimulated mouse thymocytes on flow cytometric analysis of cells indirectly stained with monoclonal antibody YHD-06. Abbreviations: carbohydrate and glycolipid nomenclature and abbreviations follow the IUPAC-IUB recommendations or the nomenclature system of Svennerholm L. (1963)J Neurochem 10:613–23.     

Cytochemical localization of GalNAc and GalNAcβ1,4Galβ1,4 disaccharide in mouse zona pellucida

Carbohydrate residues contained in the zona pellucida play a key role in the process of sperm-egg interaction. In vitro fertilization experiments have shown that a specific monoclonal antibody against GalNAcş,4Galş,4 disaccharide inhibits fertilization in mice. In the present study, the ultrastructural cytochemical localization of GalNAc residues and the GalNAcş,4Galş,4 disaccharide was carried out in ovarian and postovulatory oocytes by using lectin-gold cytochemistry and immunocytochemistry. Plant lectins SBA and DBA showed an affinity for the entire zona pellucida matrix of ovarian oocytes throughout the follicular maturation; however, immunoreactivity for GalNAcş,4Galş,4 disaccharide was not detected in ovarian oocytes at the earliest stages of follicular development but was found to be associated with the inner region of the zona matrix at the trilaminar primary follicle stage. The Golgi apparatus, vesicular aggregates, and cortical granules of the oocyte were intensely labeled by SBA and DBA throughout follicular development. Immunoreactivity to GalNAcş,4Galş,4 disaccharide was first observed in the Golgi apparatus and vesicular aggregates in trilaminar primary follicles. No immunoreactivity was observed in the cortical granules. In postovulatory oocytes, results were similar to those observed in ovarian oocytes. Our results thus suggest that (1) GalNAcş,4Galş,4 disaccharide residues are present only in the inner region of the zona pellucida and, therefore, might be involved in sperm penetration through the zona pellucida, (2) the inner and outer regions of the zona pellucida contain different oligosaccharide chains, (3) the vesicular aggregates detected in the oocyte could represent an intermediate step in the secretory pathway of zona pellucida glycoproteins and might be involved in the formation of cortical granules.     

Differential Binding to Glycotopes Among the Layers of Three Mammalian Retinal Neurons by Man-Containing N-linked Glycan, Tα (Galβ1–3GalNAcα1-), Tn (GalNAcα1-Ser/Thr) and Iβ/IIβ (Galβ1–3/4GlcNAcβ-) Reactive Lectins

Carbohydrate structures between retinal neurons and retinal pigment epithelium (RPE) play an important role in maintaining the integrity of retinal adhesion to underlying RPE, and in retinal detachment pathogenesis. Since relevant knowledge is still in the primary stage, glycotopes on the adult retina of mongrel canines (dog), micropigs and Sprague-Dawley rats were examined by lectino-histochemistry, using a panel of 16 different lectins. Paraffin sections of eyes were stained with biotinylated lectins, and visualized by streptavidin-peroxidase and diaminobenzidine staining. Mapping the affinity profiles, it is concluded that: (i) all sections of the retina reacted well with Morniga M, suggesting that N-linked glycans are present in all layers of the retina; (ii) no detectable human blood group ABH active glycotopes were found among retinal layers; (iii) outer and inner segments contained glycoconjugates rich in ligands reacting with T _α (Galβ1–3GalNAcα1-Ser/Thr) and Tn (GalNAcα1-Ser/Thr) specific lectins; (iv) cone cells of retina specifically bound peanut agglutinin (PNA), which recognizes T _α residues and could be used as a specific marker for these photoreceptors; (v) the retinas of rat, dog and pig, had a similar binding profile but with different intensity; (vi) each retinal layer had its own binding characteristic. This information may provide useful background knowledge for normal retinal physiology and miscellaneous retinal diseases, including retinal detachment (RD) and age-related macular degeneration (ARMD).     

乙肝病毒MHBst/HBx蛋白对Galβ1,3GalNAcα2,3-唾液酸转移酶的反式激活作用

PCR方法扩增乙肝病毒MHBs^t,HBx基因片段,构建真核表达载体pcDNA3.1-MHBs^t和pcDNA3.1-HBx。PCR方法从肝细胞基因组中扩增出Galβ1,3GalNAcα2,3-唾液酸转移酶（ST3Gall)启动子Psil,用Psial取代pEGFPN1的启动子pCMV构建pEGFP-N1-Psial。利用磷酸钙－DNA共沉淀的方法,将pcDNA3.1-MHBs^t,pcDNA3.1-HBx分别与pEGFP-N1-Psial瞬时共转染至正常肝细胞QGY－7701。流式细胞仪分析细胞平均荧光密度值发现MHBs^t,HBx分别将ST3Gall启动子的活性上调了35．2％和43．8％。研究了乙肝病毒MHBs^t,HBx对ST43Gall的转录调控作用,对于揭示乙肝病毒感染与唾液酸转移酶之间的关系做了非常有益的探索。     

Enzymic synthesis,chemical characterisation and Sda activity of GalNAcß1-4[NeuAcα2-3]Galß1-4GlcNAc and GalNAcß1-4[NeuAcα2-3]Galß1-4Glc

The tetrasaccharides GalNAcß1-4[NeuAc2-3]Galß1-4Glc and GalNAcß1-4[NeuAc2-3]Galß1-4GlcNAc were synthesised by enzymic transfer of GalNAc from UDP-GalNAc to 3-sialyllactose (NeuAc2-3Galß1-4Glc) and 3-sialyl-N-acetyllactosamine (NeuAc2-3Galß1-4GlcNAc). The structures of the products were established by methylation and¹H-500 MHz NMR spectroscopy. In Sd^a serological tests the product formed with 3-sialyl-N-acetyllactosamine was highly active whereas that formed with 3-sialyllactose had only weak activity.     

Sialyltransferase activity in FR3T3 cells transformed withras oncogene: decreased CMP-Neu5Ac:Galβ1-3GalNAc α-2,3-sialyltransferase

We have investigated the activity of CMP-Neu5Ac:Gal\1-3GalNAc -2,3-sialyltransferase (EC 2.4.99.4) in FR3T3 cells transformed by the Ha-ras oncogene in which we have previously demonstrated the higher expression of the -galactosidase -2,6-sialyltransferase (EC 2.4.99.1) [21]. We demonstrate that the presence of the activatedras gene decreases the activity of this specific -2,3-sialyltransferase fourfold. According to the kinetic parameters and to mixing experiments, we can assume that this decreased enzymatic activity reflects a decrease in the number of activeO-glycan -2,3-sialyltransferase polypeptides inras-transformed cells. However, no change in the binding of Peanut agglutinin was observed on the cell surface ofras-transformed FR3T3 suggesting that no change in the sialylation ofO-glycan core 1 appeared in these cells, although the activity of the -2,3-sialyltransferase was decreased.Abbreviations -2,3-ST(O) CMP-Neu5Ac:Gal1-3GalNAc-R -2,3-sialyltransferase - -2,3-ST(N/O) CMP-Neu5Ac:Gal1-3/4GlcNAc-R -2,3-sialyltransferase - -2,6-ST(N) CMP-Neu5Ac:Gal1-4GlcNAc-R -2,6-sialyltransferase - -2,6-ST(O)I CMP-Neu5Ac:R-GalNAc(1-O)Ser -2,6-sialyltransferase - -2,6-ST(O)II CMP-Neu5Ac:Neu5Ac2-3Gal1-3GalNAc-R -2,6-sialyltransferase - ASFet asialofetuin - FR3T3 Fisher rat fibroblast - FRras Ha-ras-transfected FR3T3 fibroblasts - NaCl/P_i sodium phosphate 10mm, NaCl 0.15m, pH 7.4, buffer - pNp p-nitrophenol     

The photosynthetic F1-α3β3 and α1β1 catalytic core complexes

Minimal photosynthetic catalytic F₁() core complexes, containing equimolar ratios of the and subunits, were isolated from membrane-bound spinach chloroplast CF₁ and Rhodospirillum rubrum chromatophore RrF₁. A CF₁-₃₃ hexamer and RrF₁-₁₁ dimer, which were purified from the respective F₁() complexes, exhibit lower rates and different properties from their parent F₁-ATPases. Most interesting is their complete resistance to inhibition by the general F₁ inhibitor azide and the specific CF₁ inhibitor tentoxin. These inhibitors were earlier reported to inhibit multisite, but not unisite, catalysis in all sensitive F₁-ATPases and were therefore suggested to block catalytic site cooperativity. The absence of this typical property of all F₁-ATPases in the ₁₁ dimer is consistant with the view that the dimer contains only a single catalytic site. The ₃₃ hexamer contains however all F₁ catalytic sites. Therefore the observation that CF₁-₃₃ can bind tentoxin and is stimulated by it suggests that the F₁ subunit, which is required for obtaining inhibition by tentoxin as well as azide, plays an important role in the cooperative interactions between the F₁-catalytic sites.Abbreviations CF₀F₁ chloroplast F₀F₁ - CF₁ chloroplast F₁ - CF₁ chloroplast F₁ subunit - CF₁ chloroplast F₁ subunit - CF₁() a complex containing equal amounts of the CF₁ and subunits - MF₁ mitochondrial F₁ - RrF₀F₁ Rhodospirillum rubrum F₀F₁ - RrF₁ R. rubrum F₁ - RrF₁ R. rubrum F₁ subunit - RrF₁ R. rubrum F₁ subunit - RrF₁() a complex containing equal amounts of the RrF₁ and subunits - Rubisco Ribulose-1,5-bisphosphate carboxylase - TF₁ thermophilic bacterium PS3 F₁     

Glycosidase-catalysed synthesis of glycosylated amino acids: synthesis of GalNAcα-Ser and GlcNAcβ-Ser derivatives

A glycosidase from Aspergillus oryzae catalysed the stereospecific formation of various derivatives of the Tn antigen, D-GalNAca1O-L-Ser, employing D-GalNAc-OPhNO - p as glycosyl donor and different N- and C-protected L-Ser derivatives as acceptors. The same glycosidase preparation was also useful for stereospecific preparation of D-GalNAca1O-L-Thr and D-GlcNAc1O-L-Ser derivatives. Yields were in the range 10-50% depending on the type of acceptor. Lipase from porcine pancreas was used for specific hydrolysis, generating a Tn antigen derivative with a free carboxyl group. This facilitates the use of the derivatives in e.g. solid phase synthesis of glycopeptides.     

Metabolism of 3β-hydroxy-5α- and 3β-hydroxy-5β-pregnan-20-one by leaf homogenates

Leaf homogenates of Cheiranthus cheiri, Nerium oleander, Strophanthus kombé, Digitalis purpurea, and Corchorus capsularis were ex     

5α,6α- AND 5β,6β-dichloromethylene adducts of 3β-acetoxy-5-androsten-17-one

Both the 5α, 6α- and 5β, 6β-dichloromethylene adducts ($\text{2a}$ and $\text{2b}$) of 3β-acetoxy-5-androsten-17-one ($\text{1}$) are produced when the latter is exposed to dichlorocarbene generated from chloroform and base by Phase Transfer Catalysis using ultrasound as a means of agitation. The ¹H NMR substituent effects of 5α, 6α- and 5β, 6β-dichloromethylene on the angular methyl groups (Zürcher values) are given. The ¹³C NMR spectra for both compounds are presented and discussed.     

Biosynthesis of 3α,6β-ditigloyloxytropane and 3α,6β-ditigloyloxytropan-7β-ol in Datura

Datura meteloides; plants were fed with tiglic acid-[-¹⁴C] via the roots and after 2 days the percentage incorporation into the alkaloids 3α-tigloyloxytropane, 3α,6β-ditigloyloxytropane, meteloidine and 3α,6β-ditigloyloxytropan-7β-ol were 15·2, 1·82, 2·2 and 1·8 respectively. 3α,6β-Ditigloyloxytropane was partially hydrolysed to 6β-hydroxy-3α-tigloyloxytropane which contained 58·1% of the radioactivity of the original base, whereas 3α,6β-ditigloyloxytropan-7β-ol gave meteloidine containing only 9·2% of the original activity. The results suggest that the di- and tri-hydroxytropanes may be formed by different routes.     

Occurrence of the human tumor-specific antigen structure Galβ1-3GalNAcα- (Thomsen-Friedenreich) and related structures on gut bacteria: prevalence, immunochemical analysis and structural confirmation

The Thomsen-Friedenreich antigen (TF; CD176, Galβ1-3GalNAcα-) is a tumor-specific carbohydrate antigen and a promising therapeutic target. Antibodies that react with this antigen are frequently found in the sera of healthy adults and are assumed to play a role in cancer immunosurveillance. In this study, we examined the occurrence of α-anomeric TF (TFα) on a large variety of gastrointestinal bacteria using a novel panel of well-characterized monoclonal antibodies. Reactivity with at least one anti-TF antibody was found in 13% (16 of 122) of strains analyzed. A more in-depth analysis, using monoclonal antibodies specific for α- and β-anomeric TF in combination with periodate oxidation, revealed that only two novel Bacteroides ovatus strains (D-6 and F-1), isolated from the faeces of healthy persons by TF-immunoaffinity enrichment, possessed structures that are immunochemically identical to the true TFα antigen. The TF-positive capsular polysaccharide structure of strain D-6 was characterized by mass spectrometry, monosaccharide composition analysis, glycosidase treatments and immunoblot staining with TFα- and TFβ-specific antibodies. The active antigen was identified as Galβ1-3GalNAc-, which was α-anomerically linked as a branching structure within a heptasaccharide repeating unit. We conclude that structures immunochemically identical to TFα are extremely rare on the surface of human intestinal bacteria and may only be identifiable by binding of both antibodies, NM-TF1 and NM-TF2, which recognize a complete immunomolecular imprint of the TFα structure. The two novel B. ovatus strains isolated in this study may provide a basis for the development of TF-based anti-tumor vaccines.     

整合素αVβ3与病毒感染

整合素αvβ3是一类表达于细胞表面的跨膜糖蛋白粘附分子,由α和β两种Ⅰ型膜蛋白亚单位以非共价键形式连接形成异源二聚体分子。整合素αvβ3可表达于多种细胞,细胞外信号通过不同分子可与其发生相互作用,经整合素αvβ3将细胞外信号传递至细胞内,引起钙离子、Pyk2和磷脂酰肌醇-3(PI-3)激酶等细胞内信号发生变化。整合素αvβ3在血管生成、胚胎发育、肿瘤转移、免疫应答等多种生理和病理过和中发挥着重要的作用。近几年,整合素αvβ3与病毒感染的相关研究进展迅速,本文就整合素αvβ3与病毒感染作一综述。1整合素αvβ3概述1·1整合素αv…     

Use of sialylated or sulfated derivatives and acrylamide copolymers of Galβ1,3GalNAcα- and GalNAcα- to determine the specificities of blood group T- and Tn-specific lectins and the copolymers to measure anti-T and anti-Tn antibody levels in cancer patients

Sialylated or sulfated derivatives and acrylamide copolymers of blood group T-(Gal1,3GalNAc-) and Tn-(GalNAc) haptens were studied for their interaction with the lectins of peanut (PNA),Agaricus bisporus-(ABA),Helix pomatia-(HPA) andVicia villosa B₄-(VVA), using asialo Cowper's gland mucin (ACGM), which contains both T and Tn epitopes, as the coating substrate in enzyme linked lectin assay. Both T and Tn copolymers (40 haptens) showed high affinity and strict specificity; although the T-copolymer at 0.05–0.07 µm concentration caused 50% inhibition of interaction of either PNA or ABA with ACGM, there was little inhibition of the HPA and VVA interactions at over 100 times that concentration. The Tn-copolymer at 0.02–0.05 µm inhibited HPA or VVA interaction with ACGM by 50% but gave virtually no inhibition of PNA and ABA binding. Sialyl, sulfate or methyl group substitution on C-6 of GalNAc of the T-haptene did not prevent interaction with PNA but almost abolished interaction with ABA. In contrast, sialyl or sulfate group on C-6 and sulfate on C-3 of Gal in Gal1,3GalNAc- inhibited almost completely the interaction of PNA with ACGM but had only a slight effect on the interaction of ABA; C-6 substitution with either sialic acid or sulfate on GalNAc- almost abolished the interaction of both HPA and VVA with ACGM. Preliminary studies revealed a significant depression in the serum level of anti-T (two to three-fold decrease) and anti-Tn ( two-fold decrease) antibodies in breast cancer compared with normal control subjects when the acrylamide T- and Tn-copolymers were used as coating substrates in enzyme linked immunoassays.Abbreviations PNA peanut agglutinin - ABA agaricus bisporus agglutinin - HPA helix pomatia agglutinin - VVA (B4),vicia villosa agglutinin - ACGM Asialo Copwer's gland mucin - CA carcinoma - BSA bovine serum albumin - HRP Horseradish peroxidase - ABTS 2,2-azino-di (3-ethyl-benzthiazoline sulfonate) - ELISA enzyme-linked immunosorbent assay - Al allyl - Bn benzyl - AA acrylamide - CP copolymer     

Vaccination-induced IgG response to Galα1-3GalNAc glycan epitopes in lambs protected against Haemonchus contortus challenge infection

Lambs vaccinated with Haemonchus contortus excretory/secretory (ES) glycoproteins in combination with the adjuvant Alhydrogel are protected against H. contortus challenge infection. Using glycan micro-array analysis we showed that serum from such vaccinated lambs contains IgG antibodies that recognise the glycan antigen Galα1-3GalNAc-R and GalNAcβ1-4(Fucα1-3)GlcNAc-R. Our studies revealed that H. contortus glycoproteins contain Galα1-3Gal-R as well as significant levels of Galα1-3GalNAc-R, which has not been previously reported. Extracts from H. contortus adult worms contain a galactosyltransferase acting on glycan substrates with a terminal GalNAc, indicating that the worms possess the enzymatic potential to synthesise terminal Gal-GalNAc moieties. These data illustrate that glycan micro-arrays constitute a promising technology for fast and specific analysis of serum anti-glycan antibodies in vaccination studies. In addition, this approach facilitates the discovery of novel, antigenic parasite glycan antigens that may have potential for developing glycoconjugate vaccines or utilization in diagnostics.     

3β,20α-羟基甾体脱氢酶的动力学性质

3β,20α-羟基甾体脱氢酶(3β,20α-Hydroxysteroid dehydrogenase,3β,20α-HSD)是从胎羊血中分离得到的。分子量为35kD。该酶以NADPH为辅酶,有两种底物。以孕酮为底物时,Km=30.8μmol/L,Vmax=0.7nmol min~(-1)(nmol enzyme)~(-1);以5α-二氢睾酮(5α-Dihydrotestosterone,5α-DHT)为底物时,Km=74μmol/L,Vmax=1.3nmol min~(-1)(nmol enzyme)~(-1)。5α-DHT竞争性抑制20α-还原活性,Ki=102μmol/L。16α-溴代乙酰氧基(16α-Bromo acetoxyprogesterone,16α-BAP)是3β,20α-HSD不可逆竞争性抑制剂,t_(1/2)=75min。对3β和20α还原活性的抑制常数Ki分别为23μmol/L和58μmol/L。     

Synthesis of 5α-Androstane-3α,16α,17β-triol from 3β-hydroxy-5-androsten-17-one

5α-Androstane-3α, 16α 17β-triol was synthesized from 3β-hy-droxy-5-androsten-17-one. The procedure Involved catalytic hydrogenation of 3β-hydroxy-5-androsten-17-one to 3β-hydroxy-5α-androstan-17-one. This was followed by conversion of the 3β-hydroxy group to 3α-benzoyloxy group by the Mitsunobu reaction. Further treatment with isopropenyl acetate yielded 5α-androsten-16-ene-3α, 17-diol 3-benzoate 17-acetate. This was then converted to 3α, 17-dihydroxy-5α-androstan-16-one 3-benzoate 17-acetate via the unstable epoxide intermediate after treatment with $\text{m}$-cloroperoxybenzoic acid. LiAlH₄ reduction of this compound formed 5α-androstane-3α, 16α, 17β-trlol. ¹H and ¹³C NMR of various steroids are presented to confirm the structure of this compound.