L-Methionine sulfoximine

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>210 °C (dec.) (lit.)

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L-Methionine sulfoximine has been used as a potent inhibitor of glutamine synthetase (GS) activity.


250, 500 mg in poly bottle
1, 5 g in poly bottle

Biochem/physiol Actions

As a potent inhibitor of glutamine sythetase activity (GS), this reagent has widely been used as a selection agent for plasmid integration in Chinese hamster ovary (CHO) and other mammalian cell lines. The growing demand for high yield cell banks for production of recombinant proteins for therapeutics has resulted in two major systems for selection of stable and active clones, Methotrexate selection of dihydrofolate reductase (DHFR) overexpressing cells and MSX selection of glutamine synthetase overexpressing cells. Cells are grown in the absence of glutamine in the media and inhibition of the endogenous activity of glutamine synthease results in cell death for cells lacking overexpression. The MSX-glutamine synthase selection mechanism provides benefits over that of the Methotrexate-DHFR system in that it typically requires a single amplification step and results in significant reduction of time to produce high stability, highly amplified clones. L-Methionine sulfoximine (MSX) enhances NH3 production in seedling leaves wheat, barley, corn and sorghum plants by inhibiting GS activity. MSX increases ornithine decarboxylase activity and decreases the survival rate in a model of transient cerebral ischemia.

Features and Benefits

This compound is also offered as part of Sigma′s Library of Pharmacologically Active Compounds (LOPAC®1280), a biologically annotated collection of high-quality, ready-to-screen compounds. Click here to learn more.

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LOPAC is a registered trademark of Sigma-Aldrich Co. LLC

Personal Protective Equipment

dust mask type N95 (US),Eyeshields,Gloves


NONH for all modes of transport

WGK Germany


Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

  1. Which document(s) contains shelf-life or expiration date information for a given product?

    If available for a given product, the recommended re-test date or the expiration date can be found on the Certificate of Analysis.

  2. How do I get lot-specific information or a Certificate of Analysis?

    The lot specific COA document can be found by entering the lot number above under the "Documents" section.

  3. How do I find price and availability?

    There are several ways to find pricing and availability for our products. Once you log onto our website, you will find the price and availability displayed on the product detail page. You can contact any of our Customer Sales and Service offices to receive a quote.  USA customers:  1-800-325-3010 or view local office numbers.

  4. What is the Department of Transportation shipping information for this product?

    Transportation information can be found in Section 14 of the product's (M)SDS.To access the shipping information for this material, use the link on the product detail page for the product. 

  5. What is the solubility of Product M5379, L-Methionine sulfoximine?

    We test the solubility at 50 mg/mL (0.277 M) in water; heat and/or sonication may be required.

  6. What is the solution stability of Product M5379, L-Methionine sulfoximine?

    We do not have any information available on solution stability. The following references may provide some helpful information:1. Proc. Roy. Soc., 138, 265 (1951).2. Weisbrod, R. E., and Meister, A., Studies on Glutamine Synthetase from Escherichia Coli. Formation of Pyrrolidone Carboxylate and Inhibition by Methionine Sulfoximine. J.Biol. Chem., 248(11), 3997-4002 (1973).3. Richman, P. G., et al., Inhibition of Gamma-glutamylcysteine Synthetase by L-methionine-S-sulfoximine. J. Biol. Chem., 248(19), 6684-6690 (1973).

  7. How is Product M5379, L-Methionine sulfoximine, used?

    This product has been reported as an inhibitor of glutamine synthetase by  Weisbrod, R. E., et al., J.Biol. Chem., 248(11), 3997-4002 (1973).  It has also been reported as an inhibitor of γ-glutamylcysteine synthetase by Richman, P. G., et al., J. Biol. Chem., 248(19), 6684-6690 (1973).

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I Exposito et al.
The European journal of neuroscience, 6(2), 287-291 (1994-02-01)
The effects of apomorphine, a D1-, D2-dopamine receptor agonist, on the extracellular concentrations of excitatory amino acids, glutamic and aspartic acids, and on that of their precursor, glutamine, were investigated using an intracerebral perfusion system. Apomorphine produced a concentration-related rise...
R E Isaacks et al.
Neurochemical research, 24(1), 51-59 (1999-02-11)
Ammonia causes astrocyte swelling which is abrogated by methionine sulfoximine (MSO). Since myo-inositol is an important osmolyte, we investigated the effects of ammonia and MSO on myoinositol flux in cultured astrocytes for periods up to 72 hours. Uptake of myo-inositol...
Takeshi Omasa et al.
Current pharmaceutical biotechnology, 11(3), 233-240 (2010-03-10)
Mammalian cell lines are important host cells for the industrial production of pharmaceutical proteins owing to their capacity for correct folding, assembly and post-translational modification. In particular, Chinese hamster ovary (CHO) cells are the most dependable host cells for the...
M Ginefri-Gayet et al.
European journal of pharmacology, 235(2-3), 189-196 (1993-04-28)
L-Methionine-D,L-sulfoximine (MSO) (25 micrograms) infused locally into the dorsal raphe nucleus (DRN) induced a progressive decrease in body temperature in conscious restrained rats kept at an ambient temperature of 23 degrees C. Pretreatment with (+/-)-pindolol (3 mg/kg s.c.) significantly attenuated...
Davina Chai et al.
Journal of biotechnology, 131(4), 466-472 (2007-09-11)
A key challenge in molecular breeding of orchids is the creation of efficient and reproducible gene transformation systems. In this study, we report a new transformation method utilizing L-methionine sulfoximine (MSO) as a novel agent for selection of transgenic Dendrobium...
LC/MS Analysis of L-Methionine Sulfoximine and Sulfone on Ascentis<sup>®</sup> Express OH5
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Separation of L-Methionine sulfone; L-Methionine sulfoximine; L-Methionine sulfoxide
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