Cough induced by low pH

Citric acid has been used as a tussive agent in the investigation of the cough reflex. The mechanism of cough stimulation remains unclear. We conducted studies to compare the cough response of citric acid to an organic (acetic acid) and an inorganic acid (phosphoric acid). We also compared the cough response of citric acid to capsaicin, a non-acid tussive stimulus. In study 1, 26 subjects inhaled equimolar concentrations of citric and acetic acid. In study, 2, 22 subjects inhaled citric acid and phosphoric acid in concentrations of similar pH. Eighteen subjects from study 2 completed a capsaicin cough challenge test. The cough response was recorded and the concentration causing two coughs, the cough threshold, calculated (D2). The correlation of cough thresholds between both citric and acetic acid (r = 0.79, 95% CI 0.37-0.90, P < 0.0001) and citric acid and phosphoric acid (r = 0.68, 95% CI 0.37-0.86, P = 0.0005) were significant. There was no correlation between the citric acid and capsaicin cough thresholds. These results show that an individual's cough response to acetic and phosphoric acid are similar to that caused by citric acid. Thus these acids may cause cough by a common mechanism such as disturbance of the pH of the airway surface liquid. Capsaicin does not appear to share this common pathway.

Blood pressure and heart rate in the ovine fetus: ontogenic changes and effects of fetal adrenalectomy

Ontogenic changes in baseline and 24-h rhythms of fetal arterial blood pressure (FABP) and heart rate (FHR) and their regulation by the fetal adrenal were studied in 18 fetal sheep chronically instrumented at 109-114 days gestation (GA). In the long-term study, FABP and FHR were continuously recorded from 120 days GA to spontaneous term labor (>145 days GA) in five animals. Peak times (PT) and amplitudes (Amp) of cosinor analysis were compared at 120-126, 127-133, and 134-140 days GA. Consistent, significant linear increases in FABP and linear decreases in FHR were observed in all fetuses. Significant 24-h rhythms in FABP and FHR were observed during all the time windows. In the adrenalectomy study, to test the hypothesis that fetal cortisol plays a key role in cardiovascular maturation, fetal adrenals were removed in eight animals (ADX); sham fetal adrenalectomy was performed on five animals (Con). Cortisol (4 microgram/min) was infused intravenously in four ADX fetuses from day 7 postsurgery for 7 days (ADX+F). No significant changes in PT and Amp in FABP and FHR were observed. Plasma cortisol levels remained low in Con and ADX fetuses (<4.9 ng/ml). Cortisol infusion increased fetal plasma cortisol to 22.3 +/- 3.2 ng/ml (mean +/- SE) on day 13 in ADX+F fetuses. FABP increased in control and ADX+F but not ADX fetuses; FHR decreased in control and ADX but rose in ADX+F fetuses. These results suggest that, in chronically instrumented fetal sheep at late gestation, 1) increases in FABP and decreases in FHR are maintained consistently from 120 to 140 days GA, with distinct 24-h rhythms, the PT and Amp of which remain unchanged, and 2) the physiological increase in FABP is dependent on the fetal adrenal; bilateral removal of the fetal adrenals does not prevent the ability of cortisol to produce a sustained increase in FABP.

Hypotension does not alter the antinociceptive effect of nifedipine

We explored the relationship between antinociceptive and hypotensive effects of nifedipine (NIF) injected intraperitoneally ( ip, 15 mg/kg) and epidurally (epi, 20 microM), as compared to verapamil (VER, 10 mg/kg ip) and nitroglycerin (NTG, 0.1 and 0.15 mg/kg ip). The systolic blood pressure (BP) and tail-flick (TF) latencies were measured simultaneously every 10 min for 2 hours and individual values of both measurements were correlated. The highest antinociceptive as well as hypotensive effects were both measured in the group receiving NIF epi., with the correlation coefficient r2=0.2878. Injected ip., NIF revealed similar antinociceptive effect, whereas the other studied drugs were not effective. As to the degree of hypotensive activity, NIF epi was followed by VER, NTG 0.1, NIF ip. and NTG 0.15. No significant correlation was found between BP and TF latencies in any group receiving the drugs. We concluded that the antinociceptive response, measured by the tail-flick technique, is independent of the hypotensive activity of the studied drugs, including NIF.

Chemoenzymatic synthesis of iminocyclitol derivatives: a useful library strategy for the development of selective fucosyltransfer enzymes inhibitors

A chemoenzymatic strategy has been developed for the synthesis of libraries of iminocyclitol derivatives for the discovery of new and selective fucosidase inhibitors.

Acceptor substrate-based selective inhibition of galactosyltransferases

This paper describes the discovery of glycosyl acceptor analogs as potent and selective inhibitors of alpha-1,3- and beta-1,4-galactosyltransferases. Incorporation of an appropriate aromatic group to the aglycon position of the enzyme's acceptors results in a strong inhibition, representing the first and most potent small uncharged molecules as selective inhibitors of these two enzymes and thus providing a new strategy for the development of selective glycosyltransferase inhibitors.

[The use of Cantonese pain descriptors among healthy young adults in Hong Kong]

BACKGROUND

The interpretation and expression of pain are closely related to an individual's social and cultural background. To convey messages on pain, language and words (pain descriptors) is particularly significant in assessment and evaluation of pain severity and its management. Therefore, the study of pain descriptors is crucial in clinical practice.

METHODS

It was of exploratory-descriptive design. Samples were recruited by convenience. Data were collected by structured self-administered questionnaire. Data obtained included demographic information and pain descriptors used by the subjects in various pain conditions. Data were analyzed by descriptive statistics. Pain descriptors were categorized according to nature, process, intensity, aggravating factors, accompanying symptoms and behavioral manifestation.

RESULTS

Total number of pain descriptors (in Cantonese) based on real pain experience was 3017, mean was 3 (n = 986). The commonest used descriptors was the nature of pain (41%). The intensity of pain constituted 20%. There was no significant difference in the number of pain descriptors between male and female. However, there was a significant difference between the type of pain descriptors used (Mfemale = 526, Mmale = 453, Z = -2.9729, p = 0.0029). There were also significant differences in the use of pain descriptors among the various age groups (X2 = 15.0157, df = 4, P = 0.0047) and educational levels (X2 = 11.2443, df = 4, P = 0.0240). The types of descriptors used increased with an increase in age and education levels.

CONCLUSIONS

This exploratory-descriptive study explores the use of pain descriptors among Chinese young adults in Hong Kong. The result shows that female use more pain descriptors than male. The pain descriptors that female used are mostly of nature type. The similarities and differences in findings with those of the Ho's (1991) are compared.

Structure of the haemagglutinin-esterase-fusion glycoprotein of influenza C virus

The spike glycoproteins of the lipid-enveloped orthomyxoviruses and paramyxoviruses have three functions: to recognize the receptor on the cell surface, to mediate viral fusion with the cell membrane, and to destroy the receptor. In influenza C virus, a single glycoprotein, the haemagglutinin-esterase-fusion (HEF) protein, possesses all three functions. In influenza A and B, the first two activities are mediated by haemagglutinin and the third by a second glycoprotein, neuraminidase. Here we report the crystal structure of the HEF envelope glycoprotein of influenza C virus. We have identified the receptor-binding site and the receptor-destroying enzyme (9-O-acetylesterase) sites, by using receptor analogues. The receptor-binding domain is structurally similar to the sialic acid-binding domain of influenza A haemagglutinin, but binds 9-O-acetylsialic acid. The esterase domain has a structure similar to the esterase from Streptomyces scabies and a brain acetylhydrolase. The receptor domain is inserted into a surface loop of the esterase domain and the esterase domain is inserted into a surface loop of the stem. The stem domain is similar to that of influenza A haemagglutinin, except that the triple-stranded, alpha-helical bundle diverges at both of its ends, and the amino terminus of HEF2, the fusion peptide, is partially exposed. The segregation of HEF's three functions into structurally distinct domains suggests that the entire stem region, including sequences at the amino and carboxy termini of HEF1 which precede the post-translational cleavage site between HEF1 and HEF2, forms an independent fusion domain which is probably derived from an ancestral membrane fusion protein.

Synthetic sialylphosphatidylethanolamine derivatives bind to human influenza A viruses and inhibit viral infection

We synthesized the sialylphosphatidylethanolamine (sialyl PE) derivatives Neu5Ac-PE, (Neu5Ac)2-PE, Neu5Ac-PE (amide) and Neu5Ac-PE (methyl). We examined the anti-viral effects of the derivatives on human influenza A virus infection by ELISA/virus-binding, hemagglutination inhibition, hemolysis inhibition and neutralization assays. The sialyl PE derivatives that we examined bound to A/Aichi/2/68, A/Singapore/1/57 and A/Memphis/1/71 strains of H3N2 subtype, but not to A/PR/8/34 strain of H1N1 subtype. The derivatives inhibited viral hemagglutination and hemolysis of human erythrocytes with A/Aichi/2/68 and A/Singapore/1/57 (H3N2), but not with A/PR/8/34 (H1N1). The inhibitory activity of the (Neu5Ac)2-PE derivative was the strongest of all sialyl PE derivatives (IC50, 35 microM to 40 microM). Sialyl PE derivatives also inhibited the infection of A/Aichi/2/68 in MDCK cells. Complete inhibition was observed at a concentration between 0.3 to 1.3 mM. IC50 of (Neu5Ac)2-PE was 15 microM in A/Aichi/2/68 strain. Taken together, the synthetic sialyl PE derivatives may be effective reagents against infection of some types of influenza A viruses.

Enzymatic assay of galactosyltransferase by capillary electrophoresis

The kinetic parameters of a galactosyltransferase-catalyzed reaction were determined for the first time using capillary zone electrophoresis (CZE) using the methylumbelliferyl (MU) glycoside of N-acetylglucosamine as the acceptor molecule. The CZE was performed using borate buffer and the enzymatic transformations were monitored at 214 nm. The kinetic parameters obtained for MU-GlcNAc were Km = 35.9 microM and Vmax = 7.5 micromol/min/mg, and those for UDP-Gal were Km = 115.3 microM and Vmax = 12.4 micromol/min/mg. A representative inhibition assay was also carried out using UDP as an inhibitor to give the Ki value of 83.9 microM against MU-GlcNAc. The structure of the synthetic product was also confirmed using 1H NMR spectroscopies after isolation by simple chromatography.

Synthesis of sialyl Lewis X mimetics using the Ugi four-component reaction

Application of the Ugi four-component condensation to rapidly synthesize a library of glycopeptide mimics of the tetrasaccharide SLe(x) as inhibitors of E- and P-selectin, and to study the effect of varied functionality in mimics on the inhibition is described.

Synthesis and evaluation of morpholino- and pyrrolidinosphingolipids as inhibitors of glucosylceramide synthase

This paper describes the new synthesis and evaluation of some morpholino- and pyrrolidinosphingolipids and mimics as inhibitors of glucosylceramide synthase. It was found that the pyrrolidino derivatives are generally more active than the morpholino derivatives and the best one was shown to be a nanomolar inhibitor.

The synthesis and enzymatic incorporation of sialic acid derivatives for use as tools to study the structure, activity, and inhibition of glycoproteins and other glycoconjugates

Methods have been developed for the enzymatic synthesis of complex carbohydrates and glycoproteins containing in the sialic acid moiety the heavy metal mercury or the transition-state analog phosphonate of the influenza C 9-O-acetyl-neuraminic acid esterase-catalyzed reaction. 5-Acetamido-3, 5-dideoxy-9-methylphosphono-beta-D-glycero-D-galacto-nonulopyra nosidonic acid (1), 5-acetamido-3,5-dideoxy-9-methylphosphono-2-propyl-alpha-D- glycero-D-galacto-nonulopyranosidonic acid triethylammonium salt (2), and 5-acetamido-9-thiomethylmercuric-3, 5,9-trideoxy-beta-D-glycero-D-galacto-nonulopyranosidonic acid (3) were synthesized. Compounds 1 and 2 are proposed transition state inhibitors of an esterase vital for the binding and infection of influenza C. Compound 3 was enzymatically incorporated into an oligosaccharide and a non-natural glycoprotein for use as an aid in the structure determination of these compounds by X-ray crystallography.

A chemo-enzymatic approach to the study of carbohydrate recognition in biological systems

This report describes our recent work on the study of carbohydrate-mediated cell adhesion, including the development of new methods for carbohydrate synthesis, the inhibition of enzymes involved in the cell adhesion process and the design and synthesis of carbohydrate mimetics.

Specificity of aminoglycoside antibiotics for the A-site of the decoding region of ribosomal RNA

BACKGROUND

Aminoglycoside antibiotics bind to the A-site of the decoding region of 16S RNA in the bacterial ribosome, an interaction that is probably responsible for their activity. A detailed study of the specificity of aminoglycoside binding to A-site RNA would improve our understanding of their mechanism of antibiotic activity.

RESULTS

We have studied the binding specificity of several aminoglycosides with model RNA sequences derived from the 16S ribosomal A-site using surface plasmon resonance. The 4,5-linked (neomycin) class of aminoglycosides showed specificity for wild-type A-site sequences, but the 4,6-linked class (kanamycins and gentamicins), generally showed poor specificity for the same sequences. Methylation of a cytidine in the target RNA, as found in the Escherichia coli ribosome, had negligible effects on aminoglycoside binding.

CONCLUSIONS

Although both 4,5- and 4, 6-linked aminoglycosides target the same ribosomal site, they appear to bind and effect antibiotic activity in different manners. The aminoglycosides might recognize different RNA conformations or the interaction might involve different RNA tertiary structures that are not equally sampled in our ribosome-free model. These results imply that models of ribosomal RNA must be carefully designed if the data are expected to accurately reflect biological activity.

The development of nuchal atonia associated with active (REM) sleep in fetal sheep: presence of recurrent fractal organization

The behavioral state of active or rapid eye movement sleep (REMS) is dominant during fetal life and may play an important role in brain development. One marker of this state in fetal sheep is neck nuchal muscle atonia (NA). We observed burst within burst NA patterns suggestive of recurrent fractal organization in continuous 13 day in utero recordings of NA during the third trimester. Consistent with fractal renewal processes, the cumulative mean and standard deviation (SD) diverged over this time and the tail of NA distributions fit a stable Lévy law with exponents that remained invariant over the periods of development examined. The Hurst exponent, a measure of self-affine fractals, indicated that long-range correlations among NA intervals were present throughout development. A conserved complex fractal structure is apparent in NA which may help elucidate ambiguities in defining fetal states as well as some unique properties of fetal REMS.

Analysis of the S3 and S3' subsite specificities of feline immunodeficiency virus (FIV) protease: development of a broad-based protease inhibitor efficacious against FIV, SIV, and HIV in vitro and ex vivo

The S3 and S3' subsite binding specificities of HIV and feline immunodeficiency virus proteases (FIV) proteases (PRs) have been explored by using C2-symmetric competitive inhibitors. The inhibitors evaluated contained (1S, 2R, 3R, 4S)-1,4-diamino-1, 4-dibenzyl-2,3-diol as P1 and P1' units, Val as P2 and P2' residues, and a variety of amino acids at the P3 and P3' positions. All inhibitors showed very high potency against HIV PR in vitro, and their Ki values ranged between 1.1 and 2.6 nM. In contrast to the low restriction of P3 and P3' residues observed in HIV PR, FIV PR exhibited strong preference for small hydrophobic groups at the S3 and S3' subsites. Within this series, the most effective inhibitor against FIV PR contained Ala at P3 and P3'. Its Ki of 41 nM was 415- and 170-fold lower than those of the inhibitors without the P3 and P3' moieties or with the Phe at these positions, respectively. In addition, these compounds were tested against mutant FIV PRs, which contain amino acid substitutions corresponding to those in native HIV PR at homologous sites, and their efficacy of inhibition progressively increased up to 5-fold. The most potent FIV PR inhibitor was selected for examination of its effectiveness in tissue culture, and it was able to block nearly 100% of virus production in an acute infection at 1 microg/ml (1.1 microM) against HIV, FIV, and simian immunodeficiency virus. Furthermore, it was not toxic to cells, and even after 2 months of culture there was no sign of resistance development by virus. The findings suggest that inhibitors with small P3 residue may be efficacious against a broad range of HIV variants as well as interspecies PRs.

Prostaglandin regulation of fetal plasma adrenocorticotropin and cortisol concentrations in late-gestation sheep

It is widely recognized that prostaglandins (PGs) are involved in regulation of the hypothalamo-pituitary-adrenal axis and that the activation of the fetal hypothalamo-pituitary-adrenal axis plays a central role in the process of labor in sheep. However, effects of inhibition of PG synthesis on the maternal and fetal hypothalamo-pituitary-adrenal axis during parturition have not been characterized. We examined the effect of inhibiting PG synthesis on the maternal and fetal hypothalamo-pituitary-adrenal axes during spontaneous term labor by using nimesulide, a PGH synthase (PGHS) inhibitor. Under halothane anesthesia, eight pregnant ewes were instrumented with vascular catheters and myometrial electromyogram (EMG) electrodes at 127 +/- 3 (mean +/- SEM) days gestation (dGA). After onset of labor as evaluated by EMG, nimesulide was infused to four ewes i.v. (30-mg bolus, followed by 6-h infusion at 30 mg/h). Vehicle was infused to the remaining four ewes (controls, CONT). Maternal blood and fetal blood were sampled at 1-h intervals before and during infusion to determine plasma PGE2, ACTH, and cortisol concentrations. Spontaneous labor occurred at 148 +/- 0 dGA in nimesulide-treated ewes and at 144 +/- 1 dGA in CONT ewes. We infused nimesulide from 9 +/- 2 h and vehicle from 8 +/- 2 h after the onset of labor. Maternal and fetal blood gases and pH remained unchanged in all animals. No significant changes were observed in any plasma hormone concentrations measured in CONT ewes and fetuses before and during vehicle infusion. In nimesulide-treated ewes, maternal plasma PGE2 and ACTH concentrations remained unchanged, while maternal plasma cortisol decreased significantly, recovering to baseline by 3 h. In fetuses of nimesulide-treated ewes, plasma PGE2 and ACTH levels showed significant sustained decreases after nimesulide infusion. Fetal plasma cortisol decreased significantly and returned to baseline by 5 h. These results suggest that 1) PG synthesis inhibition by nimesulide has differential effects on the ovine maternal and fetal hypothalamo-pituitary-adrenal axes during spontaneous labor, and 2) PG production plays a physiologic role in regulation of the ovine fetal hypothalamo-pituitary-adrenal axis.

Microbial aldolases and transketolases: new biocatalytic approaches to simple and complex sugars

Enzymes have become exceedingly valuable tools in organic synthesis as the reactions they catalyze generally proceed under mild conditions and in high stereo- and regioselectivity. Advances in microbiology and genetic engineering have greatly increased the availability of various enzymes. One of the most useful applications of enzyme-catalyzed chemical transformations is in the synthesis of water-soluble, polyfunctional organic molecules such as carbohydrates. As the pivotal roles that carbohydrates play in biological processes become more evident, access to these compounds becomes increasingly important. This review gives a brief overview of the use of aldolases and transketolases in the synthesis of sugars, sugar analogs, and related compounds.

Synthesis of a novel sialic acid derivative (sialylphospholipid) as an antirotaviral agent

A novel sialylphospholipid (SPL) was synthesized from N-acetylneuraminic acid (NeuAc) and phosphatidylcholine (PC) by a chemical and enzymatic method and evaluated as an inhibitor of rotavirus. PC and 1,8-octanediol were conjugated by transesterification reaction of Streptomyces phospholipase D (PLD) under a water-chloroform biphasic system to afford phosphatidyloctanol, which was condensed with a protected 2-chloro-2-deoxyneuraminic acid derivative by using silver trifluoromethanesulfonate as an activator in chloroform and converted, after deprotection, to SPL. Rhesus monkey kidney cells (MA-104) were incubated with simian (SA-11 strain) and human (MO strain) rotaviruses in the presence of SPL, and the cells infected were detected indirectly with anti-rotavirus antibody. SPL showed dose dependent inhibition against both virus strains. The concentrations required for 50% inhibition (IC50) against SA-11 and MO were 4.35 and 16.1 microM, respectively, corresponding to 10(3)- and 10(4)-fold increases in inhibition as compared to monomeric NeuAc.

Quantitative electrospray mass spectrometry for the rapid assay of enzyme inhibitors

BACKGROUND

Combinatorial chemistry has become an important method for identifying effective ligand-receptor binding, new catalysts and enzyme inhibitors. In order to distinguish the most active component of a library or to obtain structure-activity relationships of compounds in a library, an efficient quantitative assay is crucial. Electrospray mass spectrometry has become an indispensable tool for qualitatively screening combinatorial libraries and its use for quantitative analysis has recently been demonstrated.

RESULTS

This paper describes the use of quantitative electrospray mass spectrometry for screening libraries of inhibitors of enzymatic reactions, specifically the enzymatic glycosylation by beta-1,4-galactosyltransferase, which catalyzes the transfer of galactose from uridine-5'-diphosphogalactose to the 4-position of N-acetylglucosamine beta OBn (Bn: benzene) to form N-acetyllactosamine beta OBn. Our mass spectrometric screening approach showed that both nucleoside diphosphates and triphosphates inhibited galactosyltransferase while none of the nucleoside monophosphates, including uridine-5'-monophosphate, showed any inhibition. Additional libraries were generated in which the concentrations of the inhibitors were varied and, using mass spectrometry, uridine-5'-diphosphate-2-deoxy-2-fluorogalactose was identified as the best inhibitor.

CONCLUSIONS

This report introduces quantitative electrospray mass spectrometry as a rapid, sensitive and accurate quantitative assaying tool for inhibitor libraries that does not require a chromophore or radiolabeling. A viable alternative to existing analytical techniques is thus provided. The new technique will greatly facilitate the discovery of novel inhibitors against galactosyltransferase, an enzyme for which there are few potent inhibitors.

Glass bottle workers exposed to low-dose irritant fumes cough but do not wheeze

Workers exposed to irritant fumes experience symptoms both during the acute episode and afterwards. High-dose irritant exposure can result in permanent asthma, but the effects of chronic low-dose irritant exposure are not known. Glass bottle workers are exposed to irritant fumes, and have previously been reported to have an excess of symptoms. We designed a study to compare irritant-exposed glass bottle workers with hospital workers matched for socioeconomic group, area of residence, age, sex, smoking habit, and allergic history. Symptoms reported, spirometry, flow cytometric indices of lymphocyte activation, and past medical and employment histories were compared. We also investigated the prevalence of bronchial hyperresponsiveness to inhaled methacholine and the cough response after inhalation of citric acid and capsaicin. Glass bottle workers showed an excess of upper respiratory tract symptoms, cough, and shortness of breath compared with matched hospital control workers. There was a significant excess of cough induced by citric acid and capsaicin in the bottle workers. However, wheeze, baseline spirometry, flow cytometry, and methacholine challenge were not significantly different between the two groups. These findings suggest that chronic irritant exposure produces an excess of symptoms and increased cough sensitivity but not asthma.

Direct observation of aminoglycoside-RNA interactions by surface plasmon resonance

The specificity of neomycin B and related aminoglycoside antibiotics in their interaction with the Rev responsive element (RRE) of HIV-1 mRNA has been studied by directly observing the aminoglycoside-RNA complexes using surface plasmon resonance. Several different RNA sequences, each with a biotin tag, have been prepared using T7 RNA polymerase-catalyzed transcription of synthetic DNA templates and have been immobilized on a streptavidin-coated surface for the binding study. The results indicate that neomycin B is not specific for the G-rich bubble region in RRE. Rather, it appears to interact with three different sites, each with a submicromolar dissociation constant, within the 67-nucleotide domain II of RRE. Further analysis of neomycin B binding with three short synthetic RNA hairpins showed binding with submicromolar affinity and 1:1 stoichiometry in each case. This suggests that neomycin B may generally bind with this affinity to regular A-form RNA or hairpin loops. The approach described here is generally useful for understanding the fundamental interactions involved in the specific recognition of nucleic acids by small molecules which is the basis of rational drug design.

A search for pyrophosphate mimics for the development of substrates and inhibitors of glycosyltransferases

The design and synthesis of several beta-1,4-galactosyltransferase inhibitors are reported. Mimics of the pyrophosphate-Mn2+ complex were the focus of the design. Malonic, tartaric, and monosaccharide moieties were used as replacements of the pyrophosphate moiety, and galactose or azasugars with potent galactosidase inhibitory activity were used as the 'donor' component. Compound 6, in which glucose was used as the pyrophosphate-Mn2+ complex mimic and galactose as the 'donor' component, showed the best inhibitory activity towards the transferase with a Ki of 119.6 microM.

A chemoenzymatic synthesis of UDP-(2-deoxy-2-fluoro)-galactose and evaluation of its interaction with galactosyltransferase

Uridine 5'-diphospho-(2-deoxy-2-fluoro)galactose (UDP-2FGal), prepared and characterized for the first time by a chemoenzymatic method, was found to be a competitive inhibitor of beta-1,4-galactosyltransferase with a Ki value of 149 microM. This study supports that the glycosyltransferase reaction mechanism proceeds through a glycosidic cleavage transition state with sp2 character developed at the anomeric center.

Chemical selection for catalysis in combinatorial antibody libraries

For the past decade the immune system has been exploited as a rich source of de novo catalysts. Catalytic antibodies have been shown to have chemoselectivity, enantioselectivity, large rate accelerations, and even an ability to reroute chemical reactions. In many instances catalysts have been made for reactions for which there are no known natural or man-made enzymes. Yet, the full power of this combinatorial system can only be exploited if there was a system that allows for the direct selection of a particular function. A method that allows for the direct chemical selection for catalysis from antibody libraries was so devised, whereby the positive aspects of hybridoma technology were preserved and re-formatted in the filamentous phage system to allow direct selection of catalysis. This methodology is based on a purely chemical selection process, making it more general than biologically based selection systems because it is not limited to reaction products that perturb cellular machinery.