Zahra Khedri

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In order to understand the biological importance of naturally occurring sialic acid variations on disialyl structures in nature, we developed an efficient two-step multienzyme approach for the synthesis of a series of GD3 ganglioside oligosaccharides and other disialyl glycans containing a terminal Siaalpha2-8Sia component with different natural and(More)
Pasteurella multocida α2-3-sialyltransferase 1 (PmST1) is a multifunctional enzyme which has α2-6-sialyltransferase, α2-3-sialidase, and α2-3-trans-sialidase activities in addition to its major α2-3-sialyltransferase activity. The presence of the α2-3-sialidase activity of PmST1 complicates its application in enzymatic synthesis of α2-3-linked sialosides as(More)
A series of α2-3-sialylated β1-3-linked galactosides, including sialyl T-antigens, 3'-sialyl galacto-N-biose, 3'-sialyl lacto-N-biose, and their derivatives containing natural and non-natural sialic acid forms have been synthesized from simple monosaccharides using an efficient sequential two-step multienzyme approach.
Both pathogen- and tissue damage-associated molecular patterns induce inflammation through toll-like receptors (TLRs), while sialic acid-binding immunoglobulin superfamily lectin receptors (Siglecs) provide negative regulation. Here we report extensive and direct interactions between these pattern recognition receptors. The promiscuous TLR binders were(More)
Influenza viruses cause seasonal flu each year and pandemics or epidemic sporadically, posing a major threat to public health. Recently, a new influenza D virus (IDV) was isolated from pigs and cattle. Here, we reveal that the IDV utilizes 9-O-acetylated sialic acids as its receptor for virus entry. Then, we determined the crystal structures of(More)
A series of STn-MUC1 and ST-MUC1 glycopeptides containing naturally occurring and non-natural sialic acids have been chemoenzymatically synthesized from Tn-MUC1 glycopeptide using one-pot multienzyme (OPME) approaches. In situ generation of the sialyltransferase donor cytidine 5'-monophosphate-sialic acid (CMP-Sia) using a CMP-sialic acid synthetase in the(More)
Serine-rich repeat glycoproteins are adhesins expressed by commensal and pathogenic Gram-positive bacteria. A subset of these adhesins, expressed by oral streptococci, binds sialylated glycans decorating human salivary mucin MG2/MUC7, and platelet glycoprotein GPIb. Specific sialoglycan targets were previously identified for the ligand-binding regions (BRs)(More)
A library of α2-3- and α2-6-linked sialyl galactosides containing C9-modified sialic acids was synthesized from C6-modified mannose derivatives using an efficient one-pot three-enzyme system. These sialosides were used in a high-throughput sialidase substrate specificity assay to elucidate the importance of C9-OH in sialidase recognition.
Multiple sclerosis (MS) is a neurodegenerative disease that is estimated to affect over 2.3 million people worldwide. The exact cause for this disease is unknown but involves immune system attack and destruction of the myelin protein surrounding the neurons in the central nervous system. One promising class of compounds that selectively prevent the(More)
Sialidases or neuraminidases catalyze the hydrolysis of terminal sialic acid residues from sialyl oligosaccharides and glycoconjugates. Despite successes in developing potent inhibitors specifically against influenza virus neuraminidases, the progress in designing and synthesizing selective inhibitors against bacterial and human sialidases has been slow.(More)