Seeing Disulfides Via Diselenide Proxies | November 23, 2009 Issue - Vol. 87 Issue 47 | Chemical & Engineering News
Volume 87 Issue 47 | p. 32 | Concentrates
Issue Date: November 23, 2009

Seeing Disulfides Via Diselenide Proxies

Replacing cysteine with selenocysteine in proteins improves NMR observation of disulfide bridges
Department: Science & Technology
Keywords: NMR, structural biology, selenocysteine, disulfide
<em>Switching 
two cysteines to selenocysteines (asterisk) improved NMR analysis of a spider toxin without altering its native structure.</em>
Credit: Angew. Chem. Int. Ed.
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<em>Switching 
two cysteines to selenocysteines (asterisk) improved NMR analysis of a spider toxin without altering its native structure.</em>
Credit: Angew. Chem. Int. Ed.

Replacing cysteine residues in a protein with selenocysteines—in effect, replacing sulfur with selenium—improves the capability of NMR to visualize disulfide bond networks and could turn out to be a general strategy for studying protein structure, according to a report (Angew. Chem. Int. Ed. 2009, 48, 9312). Disulfide bonds between the thiol groups of two cysteine residues stabilize many proteins, such as insulin. NMR techniques are a good option for solving the structure of these proteins, but most of the techniques are difficult to use for discerning the connectivity of multiple disulfides at once. Australian researchers led by Glenn F. King of the University of Queensland have now shown that disulfide bonding can be studied via the NMR-active 77Se isotope. The team replaced two crucial cysteines in a spider toxin with selenocysteines, a change that didn’t affect the toxin’s structure or function. Then 77Se NMR experiments let the researchers unambiguously assign the protein connectivity. The approach may be applicable to larger proteins by using selenocysteines enriched with 77Se, the researchers note.

 
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