The influence of gold(i) on the mechanism of thiolate, disulfide exchange

Abstract

The mechanism of gold(i)-thiolate, disulfide exchange was investigated by using initial-rate kinetic studies, 2D ((1)H-(1)H) ROESY NMR spectroscopy, and electrochemical/chemical techniques. The rate law for exchange is overall second order, first order in gold(i)-thiolate and disulfide. 2D NMR experiments show evidence of association between gold(i)-thiolate and disulfide. Electrochemical/chemical investigations do not show evidence of free thiolate and are consistent with a mechanism involving formation of a [Au-S, S-S], four-centered metallacycle intermediate during gold(i)-thiolate, disulfide exchange.

Taking Advantage of the Morpheein Behavior of Peroxiredoxin in Bionanotechnology

“…The inborn affinity of amino acids toward metals , and the possibility to insert polyHis sequences to further expand this affinity allow Prx to bind metals and build hybrid Prx-metal nanostructures. ,, For instance, imidazole-mediated binding of Ni 2+ -coated 1.8 nm AuNPs to N-terminal polyHis-tagged Sm PrxI rings can be achieved at pH 7.6. The nanoparticles are partially trapped within the ring scaffolds thus giving to the hybrid Sm PrxI-AuNPs complexes electrical responsiveness if exposed to a 6 V bias voltage, as demonstrated by repulsive-mode electrostatic force microscopy (EFM) performed in air on samples adsorbed on silicon dioxide substrates (Figure a) .…”

“…Notably, the arrays exhibit Raman scattering enabling detection of the amino acids and alkyne molecules, the latter being distinguishable for their CC bonds in a biomolecule-silent spectral region (Figure b) . Alike the Sm PrxI-GO hybrid composites where the patterned ring shape drives stacking of GO (see section 3.2.3), the 1D assembly of AuNPs is likely to occur due to the geometrical protein complex and the interaction with the polyHis-tagged identical bottom and top surfaces; , moreover, even the native amino acids, including methionine and cysteine, at the Sm PrxI ring surface would play a role in the assembly process for being sensitive to changes of pH and ionic strength. , …”

“…Colloidal 0D NPs. The inborn affinity of amino acids toward metals 4,8 and the possibility to insert polyHis sequences to further expand this affinity allow Prx to bind metals and build hybrid Prx-metal nanostructures. 9,83,96 For instance, imidazole-mediated binding of Ni 2+ -coated 1.8 nm AuNPs to N-terminal polyHis-tagged SmPrxI rings can be achieved at pH 7.6.…”

“…Proteins can establish a plethora of specific covalent and noncovalent interactions exploiting their intrinsic and unique chemical versatility with affinity toward nanomaterials including zero-dimensional (0D) inorganic and organic nanoparticles (NPs), two-dimensional (2D) lattices such as graphene, graphene oxide (GO) and reduced GO (rGO), as well as one-dimensional (1D) carbon nanotubes . Moreover, gold (Au) and silver (Ag) nanomaterials are very suitable for conjugation with proteins due to their affinity for binding to the −SH and −S–CH 3 groups of cysteine and methionine . In addition, such chemical versatility can be improved by genetic engineering or chemical cross-linking, where ad hoc insertion of functionalities offers endless possibilities of protein engineering. − This inherent capability is further refined upon folding of the protein polymer into the tertiary and quaternary structure: during folding some amino acidic functional groups are exposed at the protein surface, creating distinct patches of chemical functionalities, and the subsequent oligomerization process patterns them in a regular manner onto the resulting 3D tertiary and quaternary assembly.…”

“…7 Moreover, gold (Au) and silver (Ag) nanomaterials are very suitable for conjugation with proteins due to their affinity for binding to the −SH and −S−CH 3 groups of cysteine and methionine. 8 In addition, such chemical versatility can be improved by genetic engineering or chemical cross-linking, where ad hoc insertion of functionalities offers endless possibilities of protein engineering. 9−11 upon folding of the protein polymer into the tertiary and quaternary structure: during folding some amino acidic functional groups are exposed at the protein surface, creating distinct patches of chemical functionalities, and the subsequent oligomerization process patterns them in a regular manner onto the resulting 3D tertiary and quaternary assembly.…”