Covalent and Selective Labeling of Proteins with Heavy Metals. Synthesis, X-ray Structure, and Reactivity Studies of N-Succinimidyl and N-Sulfosuccinimidyl Ester Organotungsten Complexes

Abstract

New functionally substituted η5-cyclopentadienyl and 2-oxaallyl (η1-enolate) tungsten complexes bearing an N-succinimidyl or an N-sulfosuccinimidyl ester have been prepared and fully characterized. The molecular structures of [η5-((succinimidooxy)carbonyl)cyclopentadienyl]methyltricarbonyltungsten(II) (2) and [η5-((succinimidooxy)carbonyl)cyclopentadienyl]iodotricarbonyltungsten(II) (5) were solved by X-ray crystallography. The reactivity of these activated esters toward a range of amines and amino acids has been studied. While the N-succinimidyl ester enolate was found to be unreactive, N-succinimidyl-substituted cyclopentadienyl complexes were quite reactive, leading to the expected stable organometallic amides. Bovine serum albumin (BSA), a 66 kDa molecular mass globular protein, could be labeled with fair yields, and conjugates were characterized by IR spectroscopy of the CO ligands. Organotungsten N-succinimidyl esters thus appear as promising reagents for the labeling of proteins with heavy metals.

Incorporation of a (Cyclopentadienyl)molybdenum Oxo Complex in MCM‐41 and Its Use as a Catalyst for Olefin Epoxidation

“…[12] Further evidence for the success of the reaction was provided by the 13 C spectrum of 3 which contained a weak resonance at δ ϭ 163.2 ppm which was assigned to the carbon atoms of the CONH groups. [13] Direct evidence for the incorporation of the covalently linked organic system in MCM-41-2 was obtained by recording 29 Si MAS NMR spectra (Figure 1).…”

Side‐chain selective and covalent labelling of proteins by organometallic complexes of heavy transition metals

“…1). The reactivity of these esters towards model amines or amino acids has been studied in detail and reported elsewhere (Salmain et al, 1993;Gorfti et al, 1996). Briefly, reaction with primary amines led to secondary amides.…”

“…The N-succinimidyl and N-sulfosuccinimidyl esters were synthesized according to established methods (Salmain et al, 1993;Gorfti et al, 1996). BSA (grade V) and HEWL (threetimes recrystallized) were purchased from Sigma and used without further purification.…”

“…With the exception of organomercury derivatives, the application of transition metal complexes with carbon ligands has been little explored, in spite of the increasing development of bioorganometallic chemistry. We have recently described the preparation of rhenium and tungsten complexes suitably functionalized in order to react with judiciously chosen protein sites (Salmain et al, 1993;Gorfti et al, 1996) They were designed from N-succinimidyl and N-sulfosuccinimidyl esters that are extensively used for the selective chemical modification of pro-teins (Means and Feeney, 1990). These two families of reagents are known to react in a very selective manner with amino groups of proteins to form stable amide bonds (Brinkley, 1992).…”

Calculating the CO-factored force constants of tricarbonyl complexes with Cs symmetry

“…Metal carbonyl complexes have unique spectroscopic properties in mid-IR range (Brimm et al 1954). Metal carbonyls should be sufficiently stable towards hydrolysis, reactive under mild conditions, selective towards particular amino acid side chain and easy to detect quantify once bound of the protein (Gorfti et al 1996). Thus, characterization of the protein conjugates can be readily performed by IR spectroscopy of the ν(CO) bands of the metal carbonyl moieties.…”