Saddam M. Muthana

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DNA and protein arrays are commonly accepted as powerful exploratory tools in research. This has mainly been achieved by the establishment of proper guidelines for quality control, allowing cross-comparison between different array platforms. As a natural extension, glycan microarrays were subsequently developed, and recent advances using such arrays have(More)
Human carcinomas can metabolically incorporate and present the dietary non-human sialic acid Neu5Gc, which differs from the human sialic acid N-acetylneuraminic acid (Neu5Ac) by 1 oxygen atom. Tumor-associated Neu5Gc can interact with low levels of circulating anti-Neu5Gc antibodies, thereby facilitating tumor progression via chronic inflammation in a(More)
Sialic acid aldolases or N-acetylneuraminate lyases (NanAs) catalyze the reversible aldol cleavage of N-acetylneuraminic acid (Neu5Ac) to form pyruvate and N-acetyl-D: -mannosamine (ManNAc). A capillary electrophoresis assay was developed to directly characterize the activities of NanAs in both Neu5Ac cleavage and Neu5Ac synthesis directions. The assay was(More)
Glycopeptides are extremely useful for basic research and clinical applications, but access to structurally defined glycopeptides is limited by the difficulties in synthesizing this class of compounds. In this study, we demonstrate that many common peptide coupling conditions used to prepare O-linked glycopeptides result in substantial amounts of(More)
Over the last 10 years, glycan microarray technology has emerged as a powerful high-throughput tool for studying the interactions of carbohydrates with a variety of biomolecules. The array format allows one to screen thousands of binding interactions in a single experiment using minimal amounts of scarce materials. More recently, this technology has been(More)
A convenient chemoenzymatic strategy for synthesizing sialosides containing a C5-diversified sialic acid was developed. The alpha2,3- and alpha2,6-linked sialosides containing a 5-azido neuraminic acid synthesized by a highly efficient one-pot three-enzyme approach were converted to C5''-amino sialosides, which were used as common intermediates for chemical(More)
para-Nitrophenol-tagged sialyl galactosides containing sialic acid derivatives in which the C5 hydroxyl group of sialic acids was systematically substituted with a hydrogen, a fluorine, a methoxyl or an azido group were successfully synthesized using an efficient chemoenzymatic approach. These compounds were used as valuable probes in high-throughput(More)
Carbohydrates play a central role in a wide range of biological processes. As with nucleic acids and proteins, modifications of specific sites within the glycan chain can modulate a carbohydrate's overall biological function. For example, acylation, methylation, sulfation, epimerization, and phosphorylation can occur at various positions within a(More)
Serum anti-glycan antibodies play important roles in many immune processes and are of particular interest as biomarkers for many diseases. Changes in anti-glycan antibodies can occur with the onset of disease or in response to stimuli such as pathogens and vaccination. Understanding relationships between anti-glycan antibody repertoires and genetic and(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.