Enzymatic synthesis of N-acetyllactosamine from lactose enabled by recombinant β1,4-galactosyltransferases

Utilising a fast and sensitive screening method based on imidazolium-tagged probes, we report unprecedented reversible activity of bacterial β1,4-galactosyltransferases to catalyse the transgalactosylation from lactose to N-acetylglucosamine to form N-acetyllactosamine in the presence of UDP. The process is demonstrated by the preparative scale synthesis of pNP-β-LacNAc from lactose using β1,4-galactosyltransferase NmLgtB-B as the only biocatalyst

United States Geological Survey Bulletin 2021-D

From abstract: Information in this report supplements the geologic map of the Stanford Canyon quadrangle that provides chemical data, thin sections, and hand specimens for each of the samples collected in the quadrangle

United States Geological Survey Bulletin 2021-E

From introduction: This report supplements similar reports prepared for the four 7.5-minute quadrangles that cover the Turkey Creek caldera and geologic map of the caldera

Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios**

The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees of drug‐to‐antibody ratio (DAR), in particular on native antibodies. Here, a glycoengineering methodology was developed to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel–Michael addition chemistry. This four‐step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions

Galactose Oxidase Enables Modular Assembly of Conjugates from Native Antibodies with High Drug-to-Antibody Ratios

The potential of antibody conjugates with high drug loading in anticancer therapy has recently been highlighted by the approval of Trastuzumab deruxtecan and Sacituzumab govitecan. These biopharmaceutical approaches have spurred interest in bioconjugation strategies with high and defined degrees antibody-to-drug (DAR) ratios, in particular on native antibodies. Here we report a glycoengineering methodology to generate antibody drug conjugates with DAR of up to eight, by combining highly selective enzymatic galactosylation and oxidation with biorthogonal tandem Knoevenagel-Michael addition chemistry. This three step approach offers a selective route to conjugates from native antibodies with high drug loading, and thus illustrates how biocatalysis can be used for the generation of biopharmaceuticals using mild reaction conditions

Development and application of a highly α2,6-selective pseudosialidase

In this manuscript we address an important gap in our current carbohydrate active enzyme toolbox, by developing a highly a2,6-selective (over a2,3-selective) de facto sialidase that is necessary both for glycan analysis and glycoconjugate remodeling. Both glycosidic linkages are commonly found in animal biology and each has been shown to have distinct biological function. Our approach is novel in that it harnesses the high selectivity of known glycosyltransferases ‘in reverse’ for effective hydrolysis, converting transferases to hydrolases by reaction engineering. More specifically, we demonstrate that the a2,6-specific pseudosialidase activity of Photobacterium sp. JT-ISH-224 a2,6-sialyltransferase can be used effectively for highly a2,6 selective hydrolysis on a broad range of analytes: small synthetic probes, isolated complex glycans and complex mixtures of glycoproteins. </p

Ion-Mobility Mass Spectrometry of Glycans and Glycopeptides Using Both Intact and Glycan Sequencing Approaches In Positive Ion Mode Facilitates Glycan Isomer and Glycan Motif Identification

High resolution glycan analysis has become an important part of biopharmaceutical API production and quality control. Liquid chromatography (LC) is now a well-established technique in this field but the resolution of similar isomeric glycan structures is still a challenge. Here we show that the addition of ion mobility spectroscopy (IMS) in a hyphenated LC-IMS-MS setting allows for the high resolution of N-glycan isomers during positive ion analysis. We have identified unique features in the IM chromatograms to help differentiate a range of isomeric N-glycans for both RFMS labelled glycans and glycopeptides.<br /

Characterisation of a bacterial galactokinase with high activity and broad substrate tolerance for chemoenzymatic synthesis of 6-aminogalactose-1-phosphate and analogues

Glycosyl phosphates are important intermediates in many metabolic pathways and are substrates for diverse carbohydrate-active enzymes. Thus, there is a need to develop libraries of structurally similar analogues that can be used as selective chemical probes in glycomics. Here, we explore chemoenzymatic cascades for the fast generation of glycosyl phosphate libraries without protecting-group strategies. The key enzyme is a new bacterial galactokinase (LgGalK) cloned from Leminorella grimontii, which was produced in Escherichia coli and shown to catalyse 1-phosphorylation of galactose. LgGalK displayed a broad substrate tolerance, being able to catalyse the 1-phosphorylation of a number of galactose analogues, including 3-deoxy-3-fluorogalactose and 4-deoxy-4-fluorogalactose, which were first reported to be substrates for wild-type galactokinase. LgGalK and galactose oxidase variant M 1 were combined in a one-pot, two-step system to synthesise 6-oxogalactose-1-phosphate and 6-oxo-2-fluorogalactose-1-phosphate, which were subsequently used to produce a panel of 30 substituted 6-aminogalactose-1-phosphate derivatives by chemical reductive amination in a one-pot, three-step chemoenzymatic process