Lac V. Lee

Identification of Novel Anthrax Lethal Factor Inhibitors Generated by Combinatorial Pictet–Spengler Reaction Followed by Screening in situ

Anthrax lethal factor (LF) is a zinc-dependent metalloprotease produced by Bacillus anthracis, the causative agent of anthrax. LF and two other plasmid encoded proteins known as edema factor (EF) and protective antigen (PA) are responsible for the virulence of Bacillus anthracis. 2, 3] The cause of LF and EF’s toxicity necessitates that they translocate from the extracellular media into the cytosol of the host cell by PA. 5] The association LF+PA is known as lethal toxin (LTx). The injection of LTx into the bloodstream of animal models is lethal, whereas the association of EF+PA, known as edema toxin (ETx), is nonvirulent without LF. When released into the bloodstream, PA binds to two extracellular receptors, 7] (Figure 1) the anthrax toxin receptor/ tumor endothelial marker 8 (ATR/TEM8) and the capillary morphogenesis protein 2 (CGM2), and becomes localized on the

Rapid discovery of potent sulfotransferase inhibitors by diversity-oriented reaction in microplates followed by in situ screening.

Rapid diversity‐oriented microplate library synthesis and in situ screening with a high‐throughput fluorescence‐based assay were used to develop potent inhibitors of β‐arylsulfotransferase IV (β‐AST‐IV). This strategy leads to facile inhibitor synthesis and study as it allows protecting‐group manipulation and product isolation from other library components to be avoided. Through repeated library formation, three aspects of inhibitor makeup, the identities of the two binding groups and the length of the linker between them, were independently optimized. Several potent inhibitors were obtained, one of which was determined to have an inhibition constant Ki of 5 nM. This compound is the most potent β‐AST‐IV inhibitor developed to date, with a Ki value more than five orders of magnitude lower than the Michaelis constant Km for the substrate whose binding it inhibits.

Synthesis of Solid-Supported Mirror-Image Sugars: A Novel Method for Selecting Receptors for Cellular-Surface Carbohydrates

We introduced a novel method, through mirror‐image phage display, for the identification of high‐affinity D‐peptides to target specific cell‐surface carbohydrates. Both 3‐deoxy‐α‐L‐manno‐2‐octulosonic acid (L‐KDO) and L‐sialic acid and an L‐sialo‐disaccharide have been synthesized and attached to a solid support for selection of high‐affinity peptide binders displayed on phages. Our initial studies in this effort produce single‐chain Fab sequences and dodecapeptides that bind to sialic acid and KDO with nanomolar and high micromolar affinity.

Synthesis of N-Acetyllactosamine Derivatives with Variation in the Aglycon Moiety for the Study of Inhibition of Sialyl Lewis x Expression

Herein we describe an inhibition study of the sialyl Lewis x (sLex) expression on a human monocytic cell line (U937), using a series of peracetylated N‐Acetyllactosamine (LacNAc) analogues with variation at the aglycon moiety. It was found that the extent of inhibition was related to the hydrophobicity and structure of the aglycon. In general, peracetylated LacNAc analogues with a naphthyl or biphenyl aglycon (3, 4, 6, and 7) were better in suppression of sLex expression than a benzyl derivative (2). Steady‐state kinetic experiments with human α‐1,3‐fucosyltransferases IV and VI (FucT IV and VI, EC 2.4.1.65) revealed that the deacetylated LacNAc‐aglycons with naphthyl (18, 19, and 20) or biphenyl (17) moieties exhibited higher affinity to the fucosyltransferases than aglycon moieties with smaller hydrophobic groups (14, 15, and 16). These results are in agreement with the findings of the U937 cell‐based experiments, and suggest that the higher enzyme affinity LacNAc‐aglycons make better acceptor decoys and, hence, the observed differences in LacNAc‐aglycon inhihitory effects on sLex expression.

Synthesis and evaluation of six-membered GDP-iminocyclitol

Fructose-diphosphate aldolase was employed in the chemoenzymatic synthesis of six-membered GDP-iminocyclitols. These compounds were evaluated for activity against α-1,3-fucosyltransferases and found to be potent inhibitors.