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Insects are considered a promising alternative protein source for food and feed, but contain significant amounts of chitin, often undesirable due to indigestibility, disagreeable texture and negative effect on nutrients intake. Fractionation strategies are thus increasingly being applied to isolate and valorize chitin separately. The analysis of chitin generally requires an intensive pretreatment to remove impurities, and derivatization to generate sufficient detector response. In this work, a liquid chromatography method, without pretreatment nor derivatization, was developed for the simultaneous determination of chitin content and degree of acetylation in non-purified samples of black soldier fly (BSF) larvae. The method is found to be more suitable, compared to traditional methods, for assessing high degrees of acetylation. For the first time, the degree of acetylation of BSF chitin (81 ± 2%) is reported. Additionally, the chitin content of BSF soft tissues is estimated at approximately 20% of the total chitin content (8.5 ± 0.1%).

N-acetyltransferases are a family of enzymes that catalyze the transfer of the acetyl moiety (–COCH3) from acetyl coenzyme A (Acetyl-CoA) to a primary amine of acceptor substrates from small molecules such as aminoglycoside to macromolecules of various proteins. In this study, the substrate selectivity of three N-acetyltransferases falling into different phylogenetic groups was probed against a series of hexosamines and synthetic peptides. GlmA from Clostridium acetobutylicum and RmNag from Rhizomucor miehei, which have been defined as glucosamine N-acetyltransferases, were herein demonstrated to be also capable of acetylating the free amino group on the very first glycine residue of peptide in spite of varied catalytic efficiency. The human recombinant N-acetyltransferase of Naa10p, however, prefers primary amine groups in the peptides as opposed to glucosamine. The varied preference of GlmA, RmNag and Naa10p probably arose from the divergent evolution of these N-acetyltransferases. The expanded knowledge of acceptor specificity would as well facilitate the application of these N-acetyltransferases in the acetylation of hexosamines or peptides.

O-Polysaccharides (O-antigens) of a number of genetically related Escherichia coli O-serogroups (O17, O44, O73, O77, and O106) and Salmonella enterica O:6,14 possess an identical main chain composed of d-GlcNAc and d-Man residues and differ from each other by the absence or presence of glucose side chains at various positions. Using two-dimensional NMR spectroscopy, we established the structure of the O-polysaccharide of E. coli O106 having two glucose side chains in a hexasaccharide repeating unit.

An extracellular acidic and thermostable chitinase (HgChi) from thermophilic Humicola grisea was purified and characterized. Enhancement in chitinase production (Qp = 2.9662 Ul?1 h?1) was achieved through derivation of optimum fermentation conditions via central composite design. H. grisea observed to produce various isoforms of chitinase, among which the major expressed form has molecular mass of about 50 kDa. Purified chitinases exhibited optimal activity at pH 3.0 and 70 °C. Chitinase showed notable stability at increasing temperatures. Half-life of chitinase is 169.06 min at optimum temperature. Chitinase has effectively catalyzed N-acetyl chitobiose (GlcNAc)2, and N-acetyl chitotriose (GlcNAc)3 and colloidal chitin. Purified chitinase from H. grisea showed high affinity towards colloidal chitin as evident by its comparatively lower Km value. Presence of metal ions viz. Mn2+, Co2+, NH4 + and Mg2+ significantly increased the chitinase activity. Thin layer chromatography (TLC) analysis revealed the significant hydrolyzing competence of HgChi for colloidal chitin, (GlcNAc)3 and (GlcNAc)2 into oligomers and N-acetyl–D-glucosamine (GlcNAc). Thermostable chitinase appeared as potential candidate for efficient conversion of chitin to bioactive oligosaccharides at industrial scale.

We report here on the preparation of a novel α-thioglycoligase that can be used for the fast and efficient synthesis of α-N-acetylglucosamine-based glycosides. Using the α-N-acetyl-glucosaminidase from Clostridium perfringens of family GH89 (according to the Carbohydrate Active Enzymes classification) as starting point, we prepared mutants in the acid/base residue glutamic acid 483 that were found to have different synthetic efficiencies (maximal yields >80% after 24 h) in the presence of an activated donor and suitable acceptors. The synthetic potential of the Glu483 alanine mutant as an α-thioglycoligase – only the third biocatalyst with this stereospecificity reported to date, and the first selective for the N-acetylglucosamine moiety – was demonstrated by producing for the first time N-acetyl-α-d-glucosaminyl azide and N-acetylglucosamine α-thioglycosides in high yields. To showcase the application of such compounds, we show that they offer the wild-type CpGH89 protection from thermal unfolding, demonstrating their potential as pharmacological chaperones for the treatment of mucopolysaccharidosis IIIB (Sanfilippo syndrome). (Figure presented.).

As a continuation of our interest in apoptosis-inducing triterpenoid saponins from Albizia genus, phytochemical investigation of the stem bark of Albizia chevalieri led to the isolation of three new oleanane-type saponins, named chevalierosides A–C (1–3). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (1H-, 13C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence. The pro-apoptotic effect of the three saponins was evaluated on two human cell lines (pancreatic carcinoma AsPC-1 and hematopoietic monocytic THP-1). Cytometric analyses showed that saponins 1–3 induced apoptosis of both human cell lines (AsPC-1 and THP-1) in a dose-dependent manner.

Two new oleanane-type saponins: β-d-xylopyranosyl-(1 → 4)-6-deoxy-α-l-mannopyranosyl-(1 → 2)-1-O-{(3β)-28-oxo-3-[(2-O-β-d-xylopyranosyl-β-d-glucopyranosyl)oxy]olean-12-en-28-yl}-β-d-glucopyranose (1) and 1-O-[(3β)-28-oxo-3-{[β-d-xylopyranosyl-(1 → 2)-α-l-

Three steroidal saponins, including astrogorgiosides A (1) and B (2) bearing acetamido-glucose moieties, and astrogorgioside C (3) with a 19-nor and bearing an aromatized B ring steroid aglycone, together with a known major saponin dimorphoside A (4), were obtained from the gorgonian Astrogorgia dumbea collected near Dongshan Island in East China Sea. Structures of these compounds were elucidated by in-depth spectral and chemical methods, including 2D-NMR, HR-ESI-MS spectra, and acidic hydrolysis. For the first time, acetamido-glucose moiety is being reported from a gorgonian. The B-ring aromatized steroid aglycone of compound 3 is also rare in marine natural products. Compounds 1-3 exhibited moderate cytotoxic activity with IC50 values of 26.8-45.6 μM against human tumor cells Bel-7402 and K562.

A new sulfated acetamido-heteropolysaccharide, HPS4-2A, was obtained by aqueous extraction followed by precipitation with ethanol and fractionation with DEAE column chromatography from Radix Hedysari. It was composed of rhamnose, arabinose, glucose, galactose and 2-acetamido-2-deoxy-D-galactose in the molar ratio of 10.09%:25.90%:25.90%:25.0%:12.30%. Elemental analysis indicated that HPS4-2A was a sulfated polysaccharide containing small amount of sulfate groups (1.87%). Partial acid hydrolysis, GC, GC-MS, 1D and 2D NMR spectroscopy analysis of the HPS4-2A revealed a predominance of glucose, galactose and 2-acetamido-2-deoxy-D-galactose linked in a highly-branched structure. Themolecular weight of HPS4-2Awas determined by HPSEC and HPSEC-MALLS. AFMstudy indicated that HPS4-2A took a highly branched conformation, which in consistent with the result studied by SEC-MALLS. Structural features of HPS4-2A were also investigated by SEM and TEM. Antioxidant assays demonstrated that HPS4-2A possessed of strong DPPH and hydroxyl radicals scavenging activities, suggesting that HPS4-2A could potentially be used as natural antioxidant.

Chemical modification has been used to introduce the unnatural amino acid γ-thialysine in place of the catalytically important Lys165 in the enzyme N-acetylneuraminic acid lyase (NAL). The Staphylococcus aureus nanA gene, encoding NAL, was cloned and expressed in E. coli. The protein, purified in high yield, has all the properties expected of a class I NAL. The S. aureus NAL which contains no natural cysteine residues was subjected to site-directed mutagenesis to introduce a cysteine in place of Lys165 in the enzyme active site. Subsequently chemical mutagenesis completely converted the cysteine into γ-thialysine through dehydroalanine (Dha) as demonstrated by ESI-MS. Initial kinetic characterisation showed that the protein containing γ-thialysine regained 17% of the wild-type activity. To understand the reason for this lower activity, we solved X-ray crystal structures of the wild-type S. aureus NAL, both in the absence of, and in complex with, pyruvate. We also report the structures of the K165C variant, and the K165-γ-thialysine enzyme in the presence, or absence, of pyruvate. These structures reveal that γ-thialysine in NAL is an excellent structural mimic of lysine. Measurement of the pH-activity profile of the thialysine modified enzyme revealed that its pH optimum is shifted from 7.4 to 6.8. At its optimum pH, the thialysine-containing enzyme showed almost 30% of the activity of the wild-type enzyme at its pH optimum. The lowered activity and altered pH profile of the unnatural amino acid-containing enzyme can be rationalised by imbalances of the ionisation states of residues within the active site when the pKa of the residue at position 165 is perturbed by replacement with γ-thialysine. The results reveal the utility of chemical mutagenesis for the modification of enzyme active sites and the exquisite sensitivity of catalysis to the local structural and electrostatic environment in NAL.

A water-soluble polysaccharide (FAAP-02), composed of N-acetyl-d- glucosamine, glucose, mannose, galactose, rhamnose arabinose, xylose and ribose, with an average molecular weight of 5169 Da, was isolated from Artemisia argyi. The antitumor and immunomodulatory activities of FAAP-02 were evaluated in Sarcoma 180 (S180) tumor-bearing mice by intraperitoneal administration. As a result, FAAP-02 significantly inhibited the growth of the S180 transplanted tumors and prolonged the survival time of the tumor-bearing mice. Moreover, FAAP-02 could obviously increase the thymus and spleen indices, the levels of serum Interleukin 2 (IL-2), Interleukin 6 (IL-6), Interleukin 12 (IL-12) and tumor necrosis factor- α (TNF-α) and the expression of CD4+ and CD8+ splenic T lymphocytes which were suppressed by the transplanted tumor or/and 5-fluorouracil (5-FU) in the mice. These results indicated that the antitumor activity of FAAP-02 might be associated with its immunostimulatory effects.

The present invention relates to a novel process for producing N-acetyl-D-Glucosamine from Glucosamine hydrochloride. More particularly this invention pertains to a novel and simple environmentally acceptable process for producing glucosamine base solution in water, with very low halide content. Glucosamine base in solution with >95% chloride ion removal is further reacted with acylating agent to produce N-acetyl-D-Glucosamine with >99% purity and chloride content of 0.1%.

The O-polysaccharide (O-antigen) of Salmonella enterica O51 was isolated by mild acid degradation of the lipopolysaccharide and its structure was established using sugar analysis and NMR spectroscopy. The O-antigen of Escherichia coli O23, whose structure was elucidated earlier, possesses a similar structure and differs only in the presence of an additional lateral α-D-Glcp residue at position 6 of the GlcNAc residue in the main chain. Sequencing of the O-antigen gene clusters of S. enterica O51 and E. coli O23 revealed the same genes with a high-level similarity. By comparison with opened gene databases, all genes expected for the synthesis of the common structure of the two O-antigens were assigned functions. It is suggested that the gene clusters of both bacteria originated from a common ancestor, whereas the O-antigen modification in E. coli O23, which, most probably, is induced by prophage genes outside the gene cluster, could be introduced after the species divergence.

2-Acetamido-2-deoxy-D-galactose (GalNAc) is a common monosaccharide found in biologically functional sugar chains, but its availability is often limited due to the lack of abundant natural sources. In order to produce GalNAc from abundantly available sugars, 2-acetamido-2-deoxy-D-glucose (GlcNAc) was converted to GalNAc by a one-pot reaction using three enzymes involved in the galacto-N-biose/lacto-N-biose I pathway of bifidobacteria. Starting the reaction with 600 mM GlcNAc, 170 mM GalNAc was produced at equilibrium in the presence of catalytic amounts of ATP and UDP-Glc under optimized conditions. GalNAc was separated from GlcNAc using water-eluting cation-exchange chromatography with a commonly available cation-exchange resin.

Three new acacic acid derivatives, named coriariosides C, D, and E (1-3) were isolated from the roots of Albizia coriaria. Their structures were elucidated on the basis of extensive 1D- and 2D-NMR studies and mass spectrometry as 3-O-[β-D-xylopyranosyl-(1 → 2)-β-D-fucopyranosyl- (1 → 6)-2-(acetamido)-2-deoxy-β-D-glucopyranosyl]-21-O-{(2E,6S)-6-O- {4-O-[(2E,6S)-2,6-dimethyl- 6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-4- O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl] -β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 2)-β-D-glucopyranosyl ester (1), 3-O-{β-D-fucopyranosyl-(1 → 6)-[β-D-glucopyranosyl-(1 → 2)]-β-D-glucopyranosyl}-21-O-{(2E,6S) -6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl] -4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl] -β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-α-L-rhamno pyranosyl-(1 → 2)-β-D-glucopyranosyl ester (2), and 3-O-[β-D-fucopyranosyl-(1 → 6)-β-D-glucopyranosyl]-21-O-{(2E, 6S)-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2, 7-dienoyl)-β-D-quinovopyranosyl]octa-2,7-dienoyl}acacic acid 28-O-β-D-glucopyranosyl ester (3).

The substrate specificity of Escherichia coli N-acetylneuraminic acid lyase was previously switched from the natural condensation of pyruvate with N-acetylmannosamine, yielding N-acetylneuraminic acid, to the aldol condensation generating N-alkylcarboxamide analogues of N-acetylneuraminic acid. This was achieved by a single mutation of Glu192 to Asn. In order to analyze the structural changes involved and to more fully understand the basis of this switch in specificity, we have isolated all 20 variants of the enzyme at position 192 and determined the activities with a range of substrates. We have also determined five high-resolution crystal structures: the structures of wild-type E. coli N-acetylneuraminic acid lyase in the presence and in the absence of pyruvate, the structures of the E192N variant in the presence and in the absence of pyruvate, and the structure of the E192N variant in the presence of pyruvate and a competitive inhibitor (2R,3R)-2,3,4-trihydroxy-N,N-dipropylbutanamide. All structures were solved in space group P21 at resolutions ranging from 1.65 A to 2.2 A. A comparison of these structures, in combination with the specificity profiles of the variants, reveals subtle differences that explain the details of the specificity changes. This work demonstrates the subtleties of enzyme-substrate interactions and the importance of determining the structures of enzymes produced by directed evolution, where the specificity determinants may change from one substrate to another.

The gene of Serratia marcescens chitinase A(chiA) was cloned by PCR. The complete gene was constructed into a pRSET vector and expressed in Escherichia coli. The recombinant enzyme was purified to > 90% homogeneity by hydrophobic interaction chromatograph

The high molecular weight of chitosan, which results in a poor solubility at neutral pH values and high viscosity aqueous solutions, limits its potential uses in the fields of food, health and agriculture. However, most of these limitations are overcome by chitosan oligosaccharides obtained by enzymatic hydrolysis of the polymer. Several commercial enzymes with different original specificities were assayed for their ability to hydrolyze a 93% deacetylation degree chitosan and compared with a chitosanase. According to the patterns of viscosity decrease and reducing end formation, three enzymes-cellulase, pepsin and lipase A-were found to be particularly suitable for hydrolyzing chitosan at a level comparable to that achieved by chitosanase. Unlike the appreciable levels of both 2-amino-2-deoxy-d-glucose and 2-acetamido-2-deoxy-d-glucose monomers released from chitosan by the other enzymes after a 20 h-hydrolysis (4.6-9.1% of the total product weight), no monomer could be detected following pepsin cleavage. As a result, pepsin produced a higher yield of chitosan oligosaccharides than the other enzymes: 52% versus as much as 46%, respectively. Low molecular weight chitosans accounted for the remaining 48% of hydrolysis products. The calculated average polymerization degree of the products released by pepsin was around 16 units after 20 h of hydrolysis. This product pattern and yield are proposed to be related to the bond cleavage specificity of pepsin and the high deacetylation degree of chitosan used as substrate. The optimal reaction conditions for hydrolysis of chitosan by pepsin were 40 °C and pH 4.5, and an enzyme/substrate ratio of 1:100 (w/w) for reactions longer than 1 h.

The invention concerns a novel chromogenic substrate based on Alizarin. The invention also concerns the uses to which this substrate can be put, and a formulation containing such a substrate. It consists therefore of a substrate to detect the presence of an enzyme activity, with the following general formula: in which: the two ketone groups of the central ring can be replaced by one group R11 (in the upper position), and by OH (in the lower position). R1 is a target part or H, and R2 is a target part or H, with at least one out of R1 and R2 being a target part, R3 is H, SO3H, Cl, Br, F, I, NO2, NH2, NR9R10, or an Acylamino Aminoaryl or Aminoacylamino group of the type NHCOX, with X being an Alkyl, Aryl or Aralkyl group or an a-amino acid residue such as Alanine, R4 is H, SO3H, Cl, Br, F, I, NO2, NH2, NR9R10, OH or an Acylamino Aminoaryl or Aminoacylamino group of the type NHCOX, with X being an Alkyl, Aryl or Aralkyl group or an α-amino acid such as Alanine, according to a modification, R3 and R4 form bonds with one another to create a ring with at least five sides, and preferably six sides. R5, R6, R7 and R8 each consist of one of the following atoms or groups of atoms: H, a halogen (particularly Cl or Br), OH, SO3H, or an Alkyl or Alkoxy group, and R9 a R10 are independently a Methyl, Alkyl, Aryl, Aralkyl group, or one (either R9 or R10) is a ring structure (Piperidine, Pyrrolidine, Morpholine, etc.) with the other (either R10 or R9) being a Hydrogen atom. The invention is particularly applicable in the field of diagnosis.

We expressed chitinase-1 (TBC-1) from tulip bulbs (Tulipa bakeri) in E. coli cells and used site-directed mutagenesis to identify amino acid residues essential for catalytic activity. Mutations at Glu-125 and Trp-251 completely abolished enzyme activity, and activity decreased with mutations at Asp-123 and Trp-172 when glycolchitin was the substrate. Activity changed with the mutations of Trp-251 to one of several amino acids with side-chains of little hydrophobicity, suggesting that hydrophobic interaction of Trp-251 is important for the activity. Molecular dynamics (MD) simulation analysis with hevamine as the model compound showed that the distance between Asp-123 and Glu-125 was extended by mutation of Trp-251. Kinetic studies of Trp-251-mutated chitinases confirmed these various phenomena. The results suggested that Glu-125 and Trp-251 are essential for enzyme activity and that Trp-251 had a direct role in ligand binding.

New compositions and methods for treating patients suffering from hepatitis-C, AIDS, aberrant apoptosis which include N-acetyl-D-glucosaminyl(β-1-4)-N-Acetyl-muramyl-L-ananyl-D-isoglutamine (GMDP) of at least 98% purity and provided either alone, as an active ingredient of blastolysine, or in combination with an aminosugar such as N-acetyl-glucosamine(NAG). The high purity GMDP has a decreased amount immunogenic impurities and demonstrates cell protection as opposed to solely immunostimulatory effects, while a synergistic cell protective effect is exhibited when GMDP in combined with NAG. The new compositions modulate FasL mediated apoptosis while simultaneously stimulating TNF-α production and further selectively inhibiting TNF-α receptor p55 (TNFR1), providing a treatment for patients suffering from hepatitis-C, AIDS or aberrant apoptosis.

A one-pot enzymatic 13C-labeling method for the 3-position of sialic acid (NeuAc) analogues has been developed using NeuAc aldolase, lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH), and nucleotide pyrophosphatase (NPP). This method consists of two steps, the first of which is degradation to 2-acetamido-2-deoxy-D-mannose (ManNAc) analogues. This degradation reaction was accelerated by a cofactor regeneration system which converts pyruvic acid into lactic acid using LDH, ADH, and β-nicotinamide adenine dinucleotide oxidized form (β-NAD+). The second step is condensation of the ManNAc analogue with [3-13C]-pyruvic acid newly added after decomposition of the cofactor by nucleotide pyrophosphatase which play a role like switch to stop conversion of pyruvic acid into lactic acid. Five different NeuAc analogues have been labeled in good yields using this newly developed one-pot enzymatic procedure. Following conversion of [3-13C]-NeuAc to CMP-[3-13C]-NeuAc, enzymatic synthesis of [3-13C]-NeuAc-α-(2→3)-[U- 13C]-Gal-β-(1→4)-GlcNAc-β-x-ovalbumin (x: hybrid type oligosaccharide) 23 and [3-13C]-NeuAc-α-(2→3)-[U- 13C]-Gal-β-(1→4)-GlcNAc-β-OMe 26 (sialyl LacNAc) was performed using bovine β-1,4-galactosyltransferase and rat recombinant α-2,3-sialyltransferase. The 1H chemical shifts of all protons in [3-13C]-NeuAc-α-(2→3)-[U-13C]-Gal-β-on a glycoprotein were assigned by 2D HMQC, 1D HSQC-TOCSY, and the herein described 1D and 2D HSQC-TOCSY-NOESY-TOCSY method. More specifically, the 7-, 8-, and 9-protons of NeuAc could be observed by this HSQC-TOCSY-NOESY-TOCSY method even with only a single 13C atom at the 3-position. In addition, 1D and 2D HMQC-NOESY spectra as well as carbon spin-lattice relaxation times (T1) were measured to compare the conformational properties and dynamic behavior of the sialylgalactoside as part of the sialyl LacNAc 26 and when bound to a glycoprotein 23. These analyses suggested that the conformational properties of sialyl LacNAc are similar for both the conjugated and unconjugated forms, and that the torsional angle of the sialyl linkage, i.e., COOH-C2NeuAc-O-C3Gal, is biased toward the anti (-146.7°) conformation. In addition, the flexibility of galactosyl ring when bound to a glycoprotein appears to be significantly restricted by the attachment of NeuAc as compared with unconjugated sialyl LacNAc.

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Carbohydrate-containing polymers which can have an HLB* of from about 10 to about 20 are disclosed. The compounds comprise a hydrophilic polymer portion, a carbohydrate portion comprising from 1 to about 20 naturally occurring, identical or different, monosaccharide units, at least one bifunctional spacer coupling the carbohydrate portion to the hydrophilic polymer portion, and a potentiator moiety. The potentiator moiety can be is a crosslinking moiety located within the hydrophilic polymer or a hydrophobic, hydrophilic or ionic moiety. Processes for the preparation and use of such polymers are also disclosed.

Topical pharmaceutical compositions, suited for the use in gynecology and urology, comprise as active principles selected Lactobacillus strains isolated from vaginal or urologic habitat of asymptomatic patients.

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Topical pharmaceutical compositions, suited for the use in gynecolocy and urology, comprise as active principles selected Lactobacillus strains isolated from vaginal or urologic habitat of asymptomatic patients.

The structure of several ceramides and cerebrosides, from three marine sponges and a soft coral collected in the Red Sea, are reported.Specifically, the structure detemination of ptiloceramide, halicerebroside A and amphicerebrosides B-F was achieved folloving suitable degradations and NMR measurements.

The 1-deoxy-1-(2-pyridylamino)alditols prepared by reductive amination of lactose, 2-acetamido-2-deoxy-D-glucose, and 2,5-anhydro-D-mannose have been characterised, and the efficiency of the reductive amination procedure, especially with 2,5-anhydro-D-mannose and 2-amino-2-deoxy-D-glucose hydrazone as starting materials, has been studied.The latter compound, which is a model for the oligosaccharide hydrazones released from glycoproteins and glycopeptides by hydrazinolysis, was first N-acetylated and the hydrazone group was found to be removed hydrolytically when a cation-exchange resin was used for deionisation.Such loss of the hydrazone group is desirable because the N-acetylated hydrazone was not efficiently derivatised by reductive amination.An amine-modified silica column was used to separate the components of a mixture of the pyridylamino derivatives of oligosaccharides from mono- to dodeca-saccharide in 20 min.A neutral fluorescent by-product, formed in all reductive aminations, was identified as (2-amino-1-pyridyl)cyanoborane and was eluted well before monosaccharide derivatives and thus did not interfere with the analysis.

Derivatives have been formed from chitins and chitosans in which the amine residues on the polyglucosamine have been modified to form the groups: (a) --N=CHR or --NHCH2 R (b) --NHR' (c) --NHR and (d) --NH--CH2 CO2 H or --NH--glyceryl where R is an aromatic moiety having at least one hydroxyl or carboxyl group, or a macrocyclic ligand R' is an aldose or ketose residue, and, R is an organometallic aldehyde residue. These derivatives are useful in chelating metals, in pharmaceutical formulations, in cosmetics, in chromatographic separations, in enzyme immobilization, as catalysts, etc. Galactomannans having selected amine-containing side chains have also been prepared by reductive amination.

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The structure of the O-specific side-chains of the lipopolysaccharide from Escherichia coli O 55 has been investigated, methylation analysis, specific degradations, and n.m.r. spectroscopy being the principal methods used. It is concluded that the O-specific side-chains are composed of pentasaccharide repeating-units having the following structure [where Col stands for colitose (3,6-dideoxy-L-xylo-hexose)].(See formula in text).

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