Rhamnose Glycoconjugates for the Recruitment of Endogenous Anti‐Carbohydrate Antibodies to Tumor Cells

Immunotherapy is a promising strategy for targeting tumors. One emerging approach is to harness the immune effector functions of natural antibodies to destroy tumor cells. Dinitrophenyl (DNP) and the galactose‐α‐1,3‐galactose (αGal) epitope are two haptens that bind endogenous antibodies. One potential alternative is the deoxysugar L ‐rhamnose. We compared these candidates by using a biosensor assay to evaluate human sera for endogenous antibody concentration, antibody isotype distribution, and longevity of antibody–hapten interactions. Antibodies recognizing α‐rhamnose are of equal or greater abundance and affinity as those recognizing αGal. Moreover, both rhamnose and αGal epitopes are more effective than DNP at recruiting the IgG antibody subtype. Exposure of tumor cells to rhamnose‐bearing glycolipids and human serum promotes complement‐mediated cytotoxicity. These data highlight the utility of α‐rhamnose‐containing glycoconjugates to direct the immune system to target cells.     

N‐Alkyl‐, 1‐C‐Alkyl‐, and 5‐C‐Alkyl‐1,5‐dideoxy‐1,5‐imino‐(l)‐ribitols as Galactosidase Inhibitors

A series of 1,5‐dideoxy‐1,5‐imino‐(l )‐ribitol (DIR) derivatives carrying alkyl or functionalized alkyl groups were prepared and investigated as glycosidase inhibitors. These compounds were designed as simplified 4‐epi‐isofagomine (4‐epi‐IFG) mimics and were expected to behave as selective inhibitors of β‐galactosidases. All compounds were indeed found to be highly selective for β‐galactosidases versus α‐glycosidases, as they generally did not inhibit coffee bean α‐galactosidase or other α‐glycosidases. Some compounds were also found to be inhibitors of almond β‐glucosidase. The N‐alkyl DIR derivatives were only modest inhibitors of bovine β‐galactosidase, with IC₅₀ values in the 30–700 μm range. Likewise, imino‐l ‐ribitol substituted at the C1 position was found to be a weak inhibitor of this enzyme. In contrast, alkyl substitution at C5 resulted in enhanced β‐galactosidase inhibitory activity by a factor of up to 1000, with at least six carbon atoms in the alkyl substituent. Remarkably, the ‘pseudo‐anomeric’ configuration in this series does not appear to play a role. Human lysosomal β‐galactosidase from leukocyte lysate was, however, poorly inhibited by all iminoribitol derivatives tested (IC₅₀ values in the 100 μm range), while 4‐epi‐IFG was a good inhibitor of this enzyme. Two compounds were evaluated as pharmacological chaperones for a GM1‐gangliosidosis cell line (R301Q mutation) and were found to enhance the mutant enzyme activity by factors up to 2.7‐fold.     

Acetylcholine Promotes Binding of α‐Conotoxin MII at α3β2 Nicotinic Acetylcholine Receptors

α‐Conotoxin MII (α‐CTxMII) is a 16‐residue peptide with the sequence GCCSNPVCHLEHSNLC, containing Cys2–Cys8 and Cys3–Cys16 disulfide bonds. This peptide, isolated from the venom of the marine cone snail Conus magus, is a potent and selective antagonist of neuronal nicotinic acetylcholine receptors (nAChRs). To evaluate the impact of channel–ligand interactions on ligand‐binding affinity, homology models of the heteropentameric α₃β₂‐nAChR were constructed. The models were created in MODELLER with the aid of experimentally characterized structures of the Torpedo marmorata‐nAChR (Tm‐nAChR, PDB ID: 2BG9) and the Aplysia californica‐acetylcholine binding protein (Ac‐AChBP, PDB ID: 2BR8) as templates for the α₃‐ and β₂‐subunit isoforms derived from rat neuronal nAChR primary amino acid sequences. Molecular docking calculations were performed with AutoDock to evaluate interactions of the heteropentameric nAChR homology models with the ligands acetylcholine (ACh) and α‐CTxMII. The nAChR homology models described here bind ACh with binding energies commensurate with those of previously reported systems, and identify critical interactions that facilitate both ACh and α‐CTxMII ligand binding. The docking calculations revealed an increased binding affinity of the α₃β₂‐nAChR for α‐CTxMII with ACh bound to the receptor, and this was confirmed through two‐electrode voltage clamp experiments on oocytes from Xenopus laevis. These findings provide insights into the inhibition and mechanism of electrostatically driven antagonist properties of the α‐CTxMIIs on nAChRs.     

A Murine Monoclonal Antibody to Glycogen: Characterization of Epitope‐Fine Specificity by Saturation Transfer Difference (STD) NMR Spectroscopy and Its Use in Mycobacterial Capsular α‐Glucan Research

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a major pathogen responsible for 1.5 million deaths annually. This bacterium is characterized by a highly unusual and impermeable cell envelope, which plays a key role in mycobacterial survival and virulence. Although many studies have focused on the composition and functioning of the mycobacterial cell envelope, the capsular α‐glucan has received relatively minor attention. Here we show that a murine monoclonal antibody (Mab) directed against glycogen cross‐reacts with mycobacterial α‐glucans, polymers of α(1–4)‐linked glucose residues with α(1–6)‐branch points. We identified the Mab epitope specificity by saturation transfer difference NMR and show that the α(1–4)‐linked glucose residues are important in glucan–Mab interaction. The minimal epitope is formed by (linear) maltotriose. Notably, a Mycobacterium mutant lacking the branching enzyme GlgB does not react with the Mab; this suggests that the α(1–6)‐branches form part of the epitope. These seemingly conflicting data can be explained by the fact that in the mutant the linear form of the α‐glucan (amylose) is insoluble. This Mab was subsequently used to develop several techniques helpful in capsular α‐glucan research. By using a capsular glucan‐screening methodology based on this Mab we were able to identify several unknown genes involved in capsular α‐glucan biogenesis. Additionally, we developed two methods for the detection of capsular α‐glucan levels. This study therefore opens new ways to study capsular α‐glucan and to identify possible targets for further research.     

Immobilized metal ions cellophane–PGMA‐grafted membranes for affinity separation of β‐galactosidase enzyme. I. Preparation and characterization

Immobilized Cu²⁺ ions affinity cellophane–poly(glycidyl methacrylate) (PGMA)‐grafted membranes have been prepared through three steps. The first step was introducing of epoxy groups to its chemical structure through grafting process with PGMA. Factors affecting the grafting process have been studied and grafting percentage (GP) up to 233% has been obtained. The second step was converting the introduced epoxy groups to sulfonic ones. It was found that maximum amount of sulfonic groups (2.7 mmol/g) was obtained with minimum GP (46.08%). The third and last step was the immobilization of Cu²⁺ ions into sulfonated grafted membranes obtained from the previous step. Maximum amount of immobilized Cu²⁺ ions was found to be 60.9 ppm per gram of polymer. The verification of the grafting and sulfonation steps has been performed through characterization of the obtained membranes using FTIR, TGA, and EDAX analysis. Finally, Cu²⁺‐immobilized membranes have been evaluated in separation of β‐galactosidase (β‐Gal) enzyme from its mixture with bovine serum albumin (BSA) in different pH medium. Maximum protein adsorption, for both proteins, has been obtained at pH range 4–4.5; as 90 and 45% for β‐Gal and BSA, respectively. The results showed high affinity toward β‐Gal separation although BSA concentration (0.5%) is 20‐folds of β‐Gal (0.025%). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,Characterization, and Initial Biological Evaluation of [99mTc]Tc‐Tricarbonyl‐labeled DPA‐α‐MSH Peptide Derivatives for Potential Melanoma Imaging

α‐Melanocyte stimulating hormone (α‐MSH) derivatives target the melanocortin‐1 receptor (MC1R) specifically and selectively. In this study, the α‐MSH‐derived peptide NAP‐NS1 (Nle‐Asp‐His‐d ‐Phe‐Arg‐Trp‐Gly‐NH₂) with and without linkers was conjugated with 5‐(bis(pyridin‐2‐ylmethyl)amino)pentanoic acid (DPA‐COOH) and labeled with [^99mTc]Tc‐tricarbonyl by two methods. With the one‐pot method the labeling was faster than with the two‐pot method, while obtaining similarly high yields. Negligible trans‐chelation and high stability in physiological solutions was determined for the [^99mTc]Tc‐tricarbonyl–peptide conjugates. Coupling an ethylene glycol (EG)‐based linker increased the hydrophilicity. The peptide derivatives displayed high binding affinity in murine B16F10 melanoma cells as well as in human MeWo and TXM13 melanoma cell homogenates. Preliminary in vivo studies with one of the [^99mTc]Tc‐tricarbonyl–peptide conjugates showed good stability in blood and both renal and hepatobiliary excretion. Biodistribution was performed on healthy rats to gain initial insight into the potential relevance of the ^99mTc‐labeled peptides for in vivo imaging.     

β‐Galactosidase immobilization into poly(hydroxyethyl methacrylate) membrane and performance in a continuous system

The activity of β‐galactosidase immobilized into a poly(2‐hydroxyethyl methacrylate) (pHEMA) membrane increased from 1.5 to 10.8 U/g pHEMA upon increase in enzyme loading. The K_m values for the free and the entrapped enzyme were found to be 0.26 and 0.81 mM, respectively. The optimum reaction temperatures for the free and the entrapped β‐galactosidase were both found to be 50°C. Similarly, the optimum reaction pH was 7.5 for both the free and the entrapped enzyme. The immobilized β‐galactosidase was characterized in a continuous system during lactose hydrolysis and the operational inactivation rate constant (k_iop) of the entrapped enzyme was found to be 3.1 × 10⁻⁵ min⁻¹. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1367–1373, 1999     

N‐Benzyl Substitution of Polyhydroxypyrrolidines: The Way to Selective Inhibitors of Golgi α‐Mannosidase II

Inhibition of the biosynthesis of complex N‐glycans in the Golgi apparatus influences progress of tumor growth and metastasis. Golgi α‐mannosidase II (GMII) has become a therapeutic target for drugs with anticancer activities. One critical task for successful application of GMII drugs in medical treatments is to decrease their unwanted co‐inhibition of lysosomal α‐mannosidase (LMan), a weakness of all known potent GMII inhibitors. A series of novel N‐substituted polyhydroxypyrrolidines was synthesized and tested with modeled GH38 α‐mannosidases from Drosophila melanogaster (GMIIb and LManII). The most potent structures inhibited GMIIb (K_i=50–76 μm , as determined by enzyme assays) with a significant selectivity index of IC₅₀(LManII)/IC₅₀(GMIIb) >100. These compounds also showed inhibitory activities in in vitro assays with cancer cell lines (leukemia, IC₅₀=92–200 μm ) and low cytotoxic activities in normal fibroblast cell lines (IC₅₀>200 μm ). In addition, they did not show any significant inhibitory activity toward GH47 Aspergillus saitoiα1,2‐mannosidase. An appropriate stereo configuration of hydroxymethyl and benzyl functional groups on the pyrrolidine ring of the inhibitor may lead to an inhibitor with the required selectivity for the active site of a target α‐mannosidase.     

Discovery of α‐Substituted Imidazole‐4‐acetic Acid Analogues as a Novel Class of ρ1 γ‐Aminobutyric Acid Type A Receptor Antagonists with Effect on Retinal Vascular Tone

The ρ‐containing γ‐aminobutyric acid type A receptors (GABA_ARs) play an important role in controlling visual signaling. Therefore, ligands that selectively target these GABA_ARs are of interest. In this study, we demonstrate that the partial GABA_AR agonist imidazole‐4‐acetic acid (IAA) is able to penetrate the blood–brain barrier in vivo; we prepared a series of α‐ and N‐alkylated, as well as bicyclic analogues of IAA to explore the structure–activity relationship of this scaffold focusing on the acetic acid side chain of IAA. The compounds were prepared via IAA from l ‐histidine by an efficient minimal‐step synthesis, and their pharmacological properties were characterized at native rat GABA_ARs in a [³H]muscimol binding assay and at recombinant human α₁β₂γ_2S and ρ₁ GABA_ARs using the FLIPR? membrane potential assay. The (+)‐α‐methyl‐ and α‐cyclopropyl‐substituted IAA analogues ((+)‐ 6 a and 6 c , respectively) were identified as fairly potent antagonists of the ρ₁ GABA_AR that also displayed significant selectivity for this receptor over the α₁β₂γ_2S GABA_AR. Both 6 a and 6 c were shown to inhibit GABA‐induced relaxation of retinal arterioles from porcine eyes.     

Characterization of a Galactosynthase Derived from Bacillus circulans β‐Galactosidase: Facile Synthesis of D‐Lacto‐ and D‐Galacto‐N‐bioside

Glycosynthases—retaining glycosidases mutated at their catalytic nucleophile—catalyze the formation of glycosidic bonds from glycosyl fluorides as donor sugars and various glycosides as acceptor sugars. Here the first glycosynthase derived from a family 35 β‐galactosidase is described. The Glu→Gly mutant of BgaC from Bacillus circulans (BgaC‐E233G) catalyzed regioselective galactosylation at the 3‐position of the sugar acceptors with α‐galactosyl fluoride as the donor. Transfer to 4‐nitophenyl α‐D ‐N‐acetyl‐glucosaminide and α‐D ‐N‐acetylgalactosaminide yielded 4‐nitophenyl α‐lacto‐N‐biose and α‐galacto‐N‐biose, respectively, in high yields (up to 98 %). Kinetic analysis revealed that the high affinity of the acceptors contributed mostly to the BgaC‐E233G‐catalyzed transglycosylation. BgaC‐E233G showed no activity with β‐(1,3)‐linked disaccharides as acceptors, thus suggesting that this enzyme can be used in “one‐pot synthesis” of LNB‐ or GNB‐containing glycans.     

Iminosugar‐Based Galactoside Mimics as Inhibitors of Galactocerebrosidase: SAR Studies and Comparison with Other Lysosomal Galactosidases

Several families of iminosugar‐based galactoside mimics were designed, synthesized, and evaluated as galactocerebrosidase (GALC) inhibitors. They were also tested as inhibitors of lysosomal β‐ and α‐galactosidases in order to find new potent and selective pharmacological chaperones for treatment of the lysosomal storage disorder, Krabbe disease. Whereas 1‐C‐alkyl imino‐L ‐arabinitols are totally inactive toward the three enzymes, 1‐C‐alkyl imino‐D ‐galactitols were found to be active only toward α‐galactosidase A. Finally, 1‐N‐iminosugars provided the best results, as 4‐epi‐isofagomine was found to be a good inhibitor of both lysosomal β‐galactosidase and GALC. Further elaboration of this structure is required to achieve selectivity between these two galactosidases.     

In situ entrapment of α‐chymotrypsin in the network of acrylamide and 2‐hydroxyethyl methacrylate copolymers

A mild and reproducible method has been developed for the entrapment of α‐chymotrypsin into a crosslinked copolymer. A porous copolymer was synthesized at 293 K by solution copolymerization of acrylamide and 2‐hydroxyethyl methacrylate. α‐Chymotrypsin was entrapped during copolymerization at different polymerization stages. The effect of crosslinking on enzyme loading and retention of its activity was examined. Copolymer with 2% crosslinking could entrap >90% of the enzyme. The activity of free and immobilized α‐chymotrypsin was determined by using N‐benzoyl‐L ‐tyrosine ethyl ester and casein as low and high molecular weight substrates respectively. Storage as well as thermal stability of the immobilized enzyme was superior to that of the free one. Effect of calcium and heavy metal ions was studied on immobilized enzyme activity. The immobilized enzyme showed little variation in activity with pH and retained 50% activity after nine cycles. The Michaelis constant K_m of the free and immobilized enzyme was estimated to be 2.7 and 4.2 × 10⁻³ mM, respectively, indicating no conformational changes during entrapment. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2996–3002, 2000     

Kinetics of the thermal inactivation of Bacillus subtilis α‐amylase and its application on the desizing of cotton fabrics

The thermal inactivation of Bacillus subtilis α‐amylase was studied in the presence and in the absence of Ca²⁺ at various temperatures. Inactivation rate constant (k), half‐life time (t_1/2), and activation energy (E_a) were determined to characterize the inactivation of the enzyme. Results obtained showed that the thermal inactivation of Bacillus subtilis α‐amylase followed a first‐order kinetics. The addition of Ca²⁺ had a good thermostabilizing effect on the enzyme. The stabilizing effect of Ca²⁺ is reflected by the increased values of the activation energy, which is about two times higher in the presence than that in the absence of 20 mM Ca²⁺, and the decreased values of the inactivation rate constants. The desizing of the cotton fabrics was performed through steaming at 100°C with Bacillus subtilis α‐amylase. The desizing efficiency seemed to be dependent on the concentration and pH value of the enzyme solution. It was found that through the steaming process with α‐amylase, the desizing ratio of the cotton fabrics could be beyond 98% and little damage happened to the fibers of the fabrics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Inhibition of Human α‐Methylacyl CoA Racemase (AMACR): a Target for Prostate Cancer

The enzyme α‐methylacyl CoA racemase (AMACR) is involved in the metabolism of branched‐chain fatty acids and has been identified as a promising therapeutic target for prostate cancer. By using the recently available human AMACR from HEK293 kidney cell cultures, we tested a series of new rationally designed inhibitors to determine the structural requirements in the acyl component. An N‐methylthiocarbamate (K_i=98 nM ), designed to mimic the proposed enzyme‐bound enolate, was found to be the most potent AMACR inhibitor reported to date.     

Galectin‐1–Asialofetuin Interaction Is Inhibited by Peptides Containing the Tyr‐Xxx‐Tyr Motif Acting on the Glycoprotein

Galectin‐1 (Gal‐1), a ubiquitous β‐galactoside‐binding protein expressed by various normal and pathological tissues, has been implicated in cancer and autoimmune/inflammatory diseases in consequence of its regulatory role in adhesion, cell viability, proliferation, and angiogenesis. The functions of Gal‐1 depend on its affinity for β‐galactoside‐containing glycoconjugates; accordingly, the inhibition of sugar binding blocks its functions, hence promising potential therapeutic tools. The Tyr‐Xxx‐Tyr peptide motifs have been reported to be glycomimetic sequences, mainly on the basis of their inhibitory effect on the Gal‐1–asialofetuin (ASF) interaction. However, the results regarding the efficacy of the Tyr‐Xxx‐Tyr motif as a glycomimetic inhibitor are still controversial. The present STD and trNOE NMR experiments reveal that the Tyr‐Xxx‐Tyr peptides studied do not bind to Gal‐1, whereas their binding to ASF is clearly detected. ¹⁵N,¹H HSQC titrations with ¹⁵N‐labeled Gal‐1 confirm the absence of any peptide–Gal‐1 interaction. These data indicate that the Tyr‐Xxx‐Tyr peptides tested in this work are not glycomimetics as they interact with ASF via an unrevealed molecular linkage.     

Synthesis and Pharmacological Evaluation of α4β2 Nicotinic Ligands with a 3‐Fluoropyrrolidine Nucleus

Nicotinic acetylcholine receptors (nAChRs) play an important role in many central nervous system disorders such as Alzheimer’s and Parkinson’s diseases, schizophrenia, and mood disorders. The α₄β₂ subtype has emerged as an important target for the early diagnosis and amelioration of Alzheimer’s disease symptoms. Herein we report a new class of α₄β₂ receptor ligands characterized by a basic pyrrolidine nucleus, the basicity of which was properly decreased through the insertion of a fluorine atom at the 3‐position, and a pyridine ring carrying at the 3‐position substituents known to positively affect affinity and selectivity toward the α₄β₂ subtype. Derivatives 3‐(((2S,4R)‐4‐fluoropyrrolidin‐2‐yl)methoxy)‐5‐(phenylethynyl)pyridine ( 11 ) and 3‐((4‐fluorophenyl)ethynyl)‐5‐(((2S,4R)‐4‐fluoropyrrolidin‐2‐yl)methoxy)pyridine ( 12 ) were found to be the most promising ligands identified in this study, showing good affinity and selectivity for the α₄β₂ subtype and physicochemical properties predictive of a relevant central nervous system penetration.     

Lipase‐catalyzed dynamic hydrolytic resolution of (R,S)‐2,2,2‐trifluoroethyl α‐chlorophenyl acetate in water‐saturated isooctane

The hydrolytic resolution of (R,S)‐2,2,2‐trifluoroethyl α‐chlorophenylacetate in water‐saturated isooctane containing Lipase MY(I) at 35 °C is selected as the best reaction condition for producing (R)‐α‐chlorophenyl acetic acid. The kinetic constants, and hence an enantiomeric ratio of 33.6, are estimated and employed for the modeling of time‐course conversions of both substrates by considering product inhibition and enzyme deactivation effects. A successful dynamic kinetic resolution is also achieved, giving the desired (R)‐α‐chlorophenylacetic acid of 93.0% yield and ee_P = 89.5% when 80 mmol dm^?3 trioctylamine acting as the racemization catalyst and enzyme activator is initially added. Copyright © 2006 Society of Chemical Industry     

A Novel Competitive Class of α‐Glucosidase Inhibitors: (E)‐1‐Phenyl‐3‐(4‐Styrylphenyl)Urea Derivatives

Competitive glycosidase inhibitors are generally sugar mimics that are costly and tedious to obtain because they require challenging and elongated chemical synthesis, which must be stereo‐ and regiocontrolled. Here, we show that readily accessible achiral (E)‐1‐phenyl‐3‐(4‐strylphenyl)ureas are potent competitive α‐glucosidase inhibitors. A systematic synthesis study shows that the 1‐phenyl moiety on the urea is critical for ensuring competitive inhibition, and substituents on both terminal phenyl groups contribute to inhibition potency. The most potent inhibitor, compound 12 (IC₅₀=8.4 μM , K_i=3.2 μM ), manifested a simple slow‐binding inhibition profile for α‐glucosidase with the kinetic parameters k₃=0.005256 μM ^?1 min^?1, k₄=0.003024 min^?1, and ${K{{{\rm app}\hfill \atop {\rm i}\hfill}}}$ =0.5753 μM .     

Cyclization of Peptides through a Urea Bond: Application to the Arg‐Gly‐Asp Tripeptide

Various synthetic cyclopeptides bind different cellular proteins with high affinity and specificity. In this study, we designed a new series of cyclic tetrapeptides containing the RGD sequence, a ligand for the α_vβ₃ integrin receptor, in which the ring closure was performed through a urea bond between the α‐amino group of the peptide and either the α‐ or the ε‐amino group of an additional lysine. Interestingly, we showed that the urea‐closed peptide had a higher affinity for α_vβ₃ receptors than a reference pentacyclopeptide. Moreover, the synthetic strategy allows coupling of the resulting cyclic tetrapeptide through the carboxylic acid moiety of its lysine residue to fluorescent molecules or drugs. In addition, this strategy could be easily adapted for the cyclization of any other peptides.     

In‐situ product removal to enhance the yield of biocatalytic reactions with competing equilibria: α‐glucosidase catalysed synthesis of disaccharides

Transglycosylations are an important class of enzyme‐catalysed reaction that occur in most living organisms and which are finding increasing application for the synthesis of therapeutic compounds. Compared with other bioconversion processes, however, they generally suffer from low product yields. This is due to the fact that in aqueous environments water is able to undergo a nucleophilic attack of the enzyme–substrate complex, increasing the rate of the competing hydrolysis reaction. The equilibrium yield of such reactions is consequently only around 10% (w/w). Here, the potential of applying in‐situ product removal (ISPR), with the boronate‐containing affinity resin Affi‐Gel® 601, to the α‐glucosidase mediated conversion of phenyl α‐D ‐glucoside to phenyl α‐maltoside has been examined. ISPR can increase the product yield from such kinetically‐controlled reactions by removing the product from the bulk aqueous phase as soon as it is formed. In this way the competing hydrolysis reaction can be prevented and conversions potentially driven to completion. Initial experiments revealed that the optimum pH of the α‐glucosidase reaction in water–acetonitrile mixtures was between 5.5 and 6.5, whereas the optimum pH for binding of the product to the Affi‐Gel® 601 resin was between 8.0 and 8.5. Despite having to compromise on both the optimal conditions for glucosidation and for binding, an increase in product yield of 25% (w/w) was still possible following the implementation of ISPR at pH 8 in an aqueous medium containing 50% (v/v) acetonitrile. Similar results were found with the β‐galactosidase catalysed synthesis of phenyl α‐galactobiose, indicating the potentially generic nature of the ISPR methodology. While these initial results are promising, they indicate the need for more highly selective resins for carbohydrate adsorption (with higher capacities) if further increases in product yield are to be obtained. © 2001 Society of Chemical Industry