Convenient synthesis of multifunctional EDTA-based chiral metal chelates substituted with an S-mesylcysteine.
We describe the synthetic route to ethylenediaminetetraacetic acid (EDTA) derivatives that can be attached to surface-exposed thiol functional groups of cysteine residues in proteins, via a methylthiosulfonate moiety that is connected in a stereochemically unique way to the C-1 carbon atom of EDTA. Such compounds can be used to align proteins in solution without the need to add liquid crystalline media, and are, therefore, of great interest for the NMR spectroscopic analysis of biomolecules. The binding constant for the paramagnetic tag to lanthanide ions was determined by measuring luminescence. For the Tb(+3)-ligand complex, a K(b) value of 6.5 x 10(17) M(-1) was obtained. This value is in excellent agreement with literature values for the related EDTA compound. In addition, it could be shown that there is no significant reduction in the luminescence intensity upon addition of a 10(4) excess of Ca2+ ions, indicating that this paramagnetic tag is compatible with buffers containing high concentrations of divalent alkaline earth ions.
Leonov
Andrei
A
Max-Planck Institute for Biophysical Chemistry, Department of NMR-Based Structural Biology, Am Fassberg 11, 37077 Göttingen, Germany.
Voigt
Brigitte
B
Rodriguez-Castañeda
Fernando
F
Sakhaii
Peyman
P
Griesinger
Christian
C
D002614:Chelating Agents / Q000138:chemical synthesis* / Q000737:chemistry; D003545:Cysteine / Q000031:analogs & derivatives* / Q000138:chemical synthesis; D004492:Edetic Acid / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008163:Luminescent Measurements / Q000379:methods; D009682:Magnetic Resonance Spectroscopy; D008698:Mesylates / Q000138:chemical synthesis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
D002614:Chelating Agents; D028581:Lanthanoid Series Elements; D008698:Mesylates; D004492:Edetic Acid; D003545:Cysteine