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Glutathione Transfe...
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Mannervik, BengtStockholms universitet,Institutionen för biokemi och biofysik
(author)
Glutathione Transferases as Efficient Ketosteroid Isomerases
- Article/chapterEnglish2021
Publisher, publication year, extent ...
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2021-11-22
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Frontiers Media SA,2021
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printrdacarrier
Numbers
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LIBRIS-ID:oai:DiVA.org:su-200692
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https://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-200692URI
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https://doi.org/10.3389/fmolb.2021.765970DOI
Supplementary language notes
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Language:English
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Summary in:English
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Classification
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Subject category:ref swepub-contenttype
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Subject category:for swepub-publicationtype
Notes
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In addition to their well-established role in detoxication, glutathione transferases (GSTs) have other biological functions. We are focusing on the ketosteroid isomerase activity, which appears to contribute to steroid hormone biosynthesis in mammalian tissues. A highly efficient GST A3-3 is present in some, but not all, mammals. The alpha class enzyme GST A3-3 in humans and the horse shows the highest catalytic efficiency with kcat/Km values of approximately 107 M−1s−1, ranking close to the most active enzymes known. The expression of GST A3-3 in steroidogenic tissues suggests that the enzyme has evolved to support the activity of 3β-hydroxysteroid dehydrogenase, which catalyzes the formation of 5-androsten-3,17-dione and 5-pregnen-3,20-dione that are substrates for the double-bond isomerization catalyzed by GST A3-3. The dehydrogenase also catalyzes the isomerization, but its kcat of approximately 1 s−1 is 200-fold lower than the kcat values of human and equine GST A3-3. Inhibition of GST A3-3 in progesterone-producing human cells suppress the formation of the hormone. Glutathione serves as a coenzyme contributing a thiolate as a base in the isomerase mechanism, which also involves the active-site Tyr9 and Arg15. These conserved residues are necessary but not sufficient for the ketosteroid isomerase activity. A proper assortment of H-site residues is crucial to efficient catalysis by forming the cavity binding the hydrophobic substrate. It remains to elucidate why some mammals, such as rats and mice, lack GSTs with the prominent ketosteroid isomerase activity found in certain other species. Remarkably, the fruit fly Drosophila melanogaster, expresses a GSTE14 with notable steroid isomerase activity, even though Ser14 has evolved as the active-site residue corresponding to Tyr9 in the mammalian alpha class.
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Ismail, AramStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)aris4283
(author)
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Lindström, Helena,1961-Stockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)heli2352
(author)
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Sjödin, BirgittaStockholms universitet,Institutionen för biokemi och biofysik(Swepub:su)bisj
(author)
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Ing, Nancy H.
(author)
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Stockholms universitetInstitutionen för biokemi och biofysik
(creator_code:org_t)
Related titles
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In:Frontiers in Molecular Biosciences: Frontiers Media SA82296-889X
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