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- Håkansson Hederos, Sofia, et al.
(författare)
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Programmed Delivery of Novel Functional Groups to the Alpha Class Glutathione Transferases
- 2003
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 42:34, s. 10260-10268
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Tidskriftsartikel (refereegranskat)abstract
- Here we describe a new route to site- and class-specific protein modification that will allow us to create novel functional proteins with artificial chemical groups. Glutathione transferases from the alpha but not the mu, pi, omega, or theta classes can be rapidly and site-specifically acylated with thioesters of glutathione (GS-thioesters) that are similar to compounds that have been demonstrated to occur in vivo. The human isoforms A1-1, A2-2, A3-3, and A4-4 from the alpha class all react with the reagent at a conserved tyrosine residue (Y9) that is crucial in catalysis of detoxication reactions. The yield of modified protein is virtually quantitative in less than 30 min under optimized conditions. The acylated product is stable for more than 24 h at pH 7 and 25 °C. The modification is reversible in the presence of excess glutathione, but the labeled protein can be protected by adding S-methylglutathione. The stability of the ester with respect to added glutathione depends on the acyl moiety. The reaction can also take place in Escherichia coli lysates doped with alpha class glutathione transferases. A control substance that lacks the peptidyl backbone required for binding to the glutathione transferases acylates surface-exposed lysines. There is some acyl group specificity since one out of the three different GS-thioesters that we tried was not able to acylate Y9.
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| 2. |
- Viljanen, Johan, et al.
(författare)
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Combinatorial Chemical Reengineering of the Alpha Class Glutathione Transferases
- 2004
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Ingår i: Bioconjugate Chemistry. - : American Chemical Society (ACS). - 1043-1802 .- 1520-4812. ; 15:4, s. 718-727
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Tidskriftsartikel (refereegranskat)abstract
- Previously, we discovered that human glutathione transferases (hGSTs) from the alpha class can be rapidly and quantitatively modified on a single tyrosine residue (Y9) using thioesters of glutathione (GS-thioesters) as acylating reagents. The current work was aimed at exploring the potential of this site-directed acylation using a combinatorial approach, and for this purpose a panel of 17 GS-thioesters were synthesized in parallel and used in screening experiments with the isoforms hGSTs A1-1, A2-2, A3-3, and A4-4. Through analytical HPLC and MALDI-MS experiments, we found that between 70 and 80% of the reagents are accepted and this is thus a very versatile reaction. The range of ligands that can be used to covalently reprogram these proteins is now expanded to include functionalities such as fluorescent groups, a photochemical probe, and an aldehyde as a handle for further chemical derivatization. This site-specific modification reaction thus allows us to create novel functional proteins with a great variety of artificial chemical groups in order to, for example, specifically tag GSTs in biological samples or create novel enzymatic function using appropriate GS-thioesters.
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