Some chemical and analytical aspects of polysaccharide modifications. II. A high-yielding, specific method for the chemical derivatization of galactose-containing polysaccharides: Oxidation with galactose oxidase followed by reductive amination

1982 ◽  
Vol 20 (12) ◽  
pp. 3399-3420 ◽  
Author(s):  
Manssur Yalpani ◽  
Laurance D. Hall
Keyword(s):  
Reductive Amination ◽  
Galactose Oxidase ◽  
Specific Method ◽  
Chemical Derivatization

scholarly journals Chemo-enzymatic modification of poly-N-acetyllactosamine (LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) based on galactose oxidase treatment

2012 ◽  
Vol 8 ◽  
pp. 712-725 ◽  
Author(s):  
Christiane E Kupper ◽  
Ruben R Rosencrantz ◽  
Birgit Henßen ◽  
Helena Pelantová ◽  
Stephan Thönes ◽  
...  
Keyword(s):  
Reductive Amination ◽  
Chemical Conversion ◽  
Product Formation ◽  
Galactose Oxidase ◽  
Binding Motif ◽  
Enzymatic Modification ◽  
Specific Interest ◽  
Subsequent Reduction ◽  
Binding Studies ◽  
Terminal Galactose

The importance of glycans in biological systems is highlighted by their various functions in physiological and pathological processes. Many glycan epitopes on glycoproteins and glycolipids are based on N-acetyllactosamine units (LacNAc; Galβ1,4GlcNAc) and often present on extended poly-LacNAc glycans ([Galβ1,4GlcNAc] n ). Poly-LacNAc itself has been identified as a binding motif of galectins, an important class of lectins with functions in immune response and tumorigenesis. Therefore, the synthesis of natural and modified poly-LacNAc glycans is of specific interest for binding studies with galectins as well as for studies of their possible therapeutic applications. We present the oxidation by galactose oxidase and subsequent chemical or enzymatic modification of terminal galactose and N-acetylgalactosamine residues of poly-N-acetyllactosamine (poly-LacNAc) oligomers and N,N-diacetyllactosamine (LacDiNAc) by galactose oxidase. Product formation starting from different poly-LacNAc oligomers was characterised and optimised regarding formation of the C6-aldo product. Further modification of the aldehyde containing glycans, either by chemical conversion or enzymatic elongation, was established. Base-catalysed β-elimination, coupling of biotin–hydrazide with subsequent reduction to the corresponding hydrazine linkage, and coupling by reductive amination to an amino-functionalised poly-LacNAc oligomer were performed and the products characterised by LC–MS and NMR analysis. Remarkably, elongation of terminally oxidised poly-LacNAc glycans by β3GlcNAc- and β4Gal-transferase was also successful. In this way, a set of novel, modified poly-LacNAc oligomers containing terminally and/or internally modified galactose residues were obtained, which can be used for binding studies and various other applications.

Analysis of Phenols by Chemical Derivatization. IV. Rapid and Sensitive Method for Analysis of 21 Chlorophenols by Improved Chloroacetylation Procedures

1985 ◽  
Vol 68 (3) ◽  
pp. 422-426
Author(s):  
Hing-Biu Lee ◽  
Robert L Hong-You ◽  
Alfred S Y Chau
Keyword(s):  
Organic Compounds ◽  
Natural Water ◽  
Capillary Column ◽  
Fused Silica ◽  
Specific Method ◽  
Chemical Derivatization ◽  
Fused Silica Capillary ◽  
Silica Capillary Column ◽  
Silica Capillary

Abstract A quantitative, rapid, sensitive, and isomer-specific method for the analysis of chlorophenols in natural water by in situ chloroacetylation is presented. Without pre-extraction, phenols in water are chloroacetylated by chloroacetic anhydride in the presence of K2CO3. Because of differences in reaction kinetics and stability, various chloroacetates were removed from the reaction mixture at different intervals. If analysis of other classes of neutral organic compounds is also required, a more elaborate procedure involving solvent extraction of organic compounds and back-extraction of phenols into K2CO3 solution followed by chloroacetylation is proposed. When a 12 m OV-1 fused silica capillary column was used, 22 phenol chloroacetates were easily resolved in a single run. Using distilled and natural water samples, this method has been validated and shown to be applicable over a concentration range of 0.1 to 100 μg/L of the phenols studied.

A specific method for d-galactose quantitative determination: A modification of the d-galactose oxidase assay

1981 ◽  
Vol 93 (2) ◽  
pp. 167-175 ◽  
Author(s):  
Marta Elena Fernández de Recondo ◽  
Beatriz Fernández de Arcuri ◽  
Eduardo F. Recondo
Keyword(s):  
Quantitative Determination ◽  
Galactose Oxidase ◽  
Specific Method

Functional Fractionation of Platelets: Aggregation Kinetics and Glycoprotein Labeling of Differing Platelet Populations

1982 ◽  
Vol 48 (02) ◽  
pp. 211-216 ◽  
Author(s):  
V M Haver ◽  
A R L Gear
Keyword(s):  
Galactose Oxidase ◽  
Aggregation Kinetics ◽  
Maximal Rate ◽  
Membrane Glycoproteins ◽  
Whole Cells ◽  
Reversible Aggregation ◽  
Significant Difference ◽  
Small Doses ◽  
Major Loss ◽  
Kinetics Of

SummaryPlatelet heterogeneity has been studied with a technique called functional fractionation which employs gentle centrifugation to yield subpopulations (“reactive” and “less-reactive” platelets) after exposure to small doses of aggregating agent. Aggregation kinetics of the different platelet populations were investigated by quenched-flow aggregometry. The large, “reactive” platelets were more sensitive to ADP (Ka = 1.74 μM) than the smaller “less-reactive” platelets (Ka = 4.08 μM). However, their maximal rate of aggregation (Vmax, % of platelets aggregating per sec) of 23.3 was significantly lower than the “less-reactive” platelets (Vmax = 34.7). The “reactive” platelets had a 2.2 fold higher level of cyclic AMP.Platelet glycoproteins were labeled using the neuraminidase-galactose oxidase – [H3]-NaBH4 technique. When platelets were labeled after reversible aggregation, the “reactive” platelets showed a two-fold decrease in labeling efficiency (versus control platelets). However, examination of whole cells or membrane preparations from reversibly aggregated platelets revealed no significant difference in Coomassie or PAS (Schiff) staining.These results suggest that the large, “reactive” platelets are more sensitive to ADP but are not hyperaggregable in a kinetic sense. Reversible aggregation may cause a re-orientation of membrane glycoproteins that is apparently not characterized by a major loss of glycoprotein material.

A SIMPLE METHOD FOR THE DETECTION OF URINARY UNCONJUGATED CORTISOL BY PAPER CHROMATOGRAPHY

1964 ◽  
Vol 47 (3) ◽  
pp. 466-468 ◽  
Author(s):  
S. B. Pal
Keyword(s):  
Paper Chromatography ◽  
Human Urine ◽  
Specific Method ◽  
Simple Method ◽  
Normal Human

ABSTRACT Unconjugated corticosteroids are extracted from normal human urine and the urine of patients with rheumatic disorders treated with synthetic corticosteroids and corticotrophin. A simple and specific method using paper chromatography has been developed to detect the unconjugated cortisol in urine.

Selective Functionalization at N2-Position of Guanine in Oligonucleotides via Reductive Amination

2020 ◽  
Author(s):  
Bapurao Bhoge ◽  
Ishu Saraogi
Keyword(s):  
Organic Chemistry ◽  
Chemical Biology ◽  
Reductive Amination ◽  
The Other ◽  
Dna Oligomers ◽  
Site Specific ◽  
Wide Applicability ◽  
Dna Oligonucleotides ◽  
Selective Functionalization

Chemo- and site-specific modifications in oligonucleotides have wide applicability as mechanistic probes in chemical biology. Here we have employed a classical reaction in organic chemistry, reductive amination, to selectively functionalize the N<sup>2</sup>-amine of guanine/2’-deoxyguanine monophosphate. This method specifically modifies guanine in several tested DNA oligonucleotides, while leaving the other bases unaffected. Using this approach, we have successfully incorporated desired handles chemoselectively into DNA oligomers.

Bringing Biocatalysis into the Deuteration Toolbox

2019 ◽  
Author(s):  
Jack Rowbotham ◽  
Oliver Lenz ◽  
Holly Reeve ◽  
Kylie Vincent
Keyword(s):  
Late Stage ◽  
Hydrogen Isotope ◽  
Reductive Amination ◽  
Mechanistic Studies ◽  
Ambient Conditions ◽  
Synthetic Pathway ◽  
Drug Candidates ◽  
Isotopic Selectivity ◽  
Reducing Equivalents

<p></p><p>Chemicals labelled with the heavy hydrogen isotope deuterium (<sup>2</sup>H) have long been used in chemical and biochemical mechanistic studies, spectroscopy, and as analytical tracers. More recently, demonstration of selectively deuterated drug candidates that exhibit advantageous pharmacological traits has spurred innovations in metal-catalysed <sup>2</sup>H insertion at targeted sites, but asymmetric deuteration remains a key challenge. Here we demonstrate an easy-to-implement biocatalytic deuteration strategy, achieving high chemo-, enantio- and isotopic selectivity, requiring only <sup>2</sup>H<sub>2</sub>O (D<sub>2</sub>O) and unlabelled dihydrogen under ambient conditions. The vast library of enzymes established for NADH-dependent C=O, C=C, and C=N bond reductions have yet to appear in the toolbox of commonly employed <sup>2</sup>H-labelling techniques due to requirements for suitable deuterated reducing equivalents. By facilitating transfer of deuterium atoms from <sup>2</sup>H<sub>2</sub>O solvent to NAD<sup>+</sup>, with H<sub>2</sub> gas as a clean reductant, we open up biocatalysis for asymmetric reductive deuteration as part of a synthetic pathway or in late stage functionalisation. We demonstrate enantioselective deuteration via ketone and alkene reductions and reductive amination, as well as exquisite chemo-control for deuteration of compounds with multiple unsaturated sites.</p><p></p>

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