DescriptionSynthetic biomimetic compounds play crucial roles in virtually all aspects of biology and medicine. Their continual development contributes towards understanding and manipulating the normal action of enzymes and other proteins as well as in the development of new drugs. Herein, the novel synthesis of biomimetic enzyme inhibitors, including GlcNAc-thiazolines, GlcNAc-thiolsulfonates, and seleninates, selenonates, and various other organoselenium compounds, is reported. Evaluation of these biomimetics against N-acetyl-β-hexosaminidases, protein tyrosine phosphatases, and some nucleoside processing enzymes is described. Evidence toward elucidation of several reaction mechanisms linked to the synthesis and inhibition of these compounds is also presented.