Current Drug Targets

Francis J. Castellino
Kleiderer-Pezold Professor of Biochemistry
Director, W.M. Keck Center for Transgene Research
Dean Emeritus, College of Science
230 Raclin-Carmichael Hall, University of Notre Dame
Notre Dame, IN 46556
USA

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Inhibition of Human Serine Racemase, an Emerging Target for Medicinal Chemistry

Author(s): Jana Jiraskova-Vanickova, Rudiger Ettrich, Barbora Vorlova, Hillary E. Hoffman, Martin Lepsik, Petr Jansa, Jan Konvalinka.

Abstract:

Proteins of glutamatergic NMDA receptor signaling pathways have been studied as targets for intervention in a variety of neuropathological conditions, including neurodegenerations, epilepsy, neuropathic pain, drug addiction, and schizophrenia. High activity NMDA-blocking agents have been designed to treat some of these disorders; however, their effect is often compromised by undesirable side effects. Therefore, alternative ways of modulating NMDA receptor function need to be sought after.

The opening of the NMDA receptor ion channel requires occupation of two distinct binding sites, the glutamate site and the glycine site. It has been shown that D-serine, rather than glycine, can trigger the physiological NMDA receptor function. D-serine is a product of the activity of a specific enzyme, serine racemase (SR), which was identified a decade ago. SR has therefore emerged as a new potential target for the NMDA-receptor-based diseases. There is evidence linking increased levels of D-Ser to amyotrophic lateral sclerosis and Alzheimer's disease and decreased concentrations of Dserine to schizophrenia.

SR is a pyridoxal-5'-phosphate dependent enzyme found in the cytosol of glial and neuronal cells. It is activated by ATP, divalent cations like Mg2+ or Ca2+, and reducing agents. This paper reviews the present literature on the activity and inhibition of mammalian SRs. It summarizes approaches that have been applied to design SR inhibitors and lists the known active compunds. Based on biochemical and docking analyses, i) we delineate for the first time the ATP binding site of human SR, ii) we suggest possible mechanisms of action for the active compounds. In the end, we discuss the SR features that make the discovery of its inhibitors a challenging, yet very important, task of medicinal chemistry.

Keywords: Amino acid analogs, L-erythro-3-hydroxyaspartate (L-EHA), D-serine, neurodegenerative diseases, NMDA receptors, pyridoxal-5'-phosphate (PLP), serine racemase, Alzheimer's disease, neuronal cells, enzyme

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Article Details

VOLUME: 12
ISSUE: 7
Year: 2011
Page: [1037 - 1055]
Pages: 19
DOI: 10.2174/138945011795677755
Price: $58