Mass spectrometry has played a key role in identifying the members of series gold clusters, which enabled development magic-number cluster theory. The successes system have yet to be repeated another metal system, however. Silver clusters particular proven challenging due their relative instability compared with clusters. Using well-characterized nanocluster, Au(25)(SG)(18), we present optimized electrospray ionization mass (ESI-MS) instrumental parameters for maximal transmission intact...

A general catalytic methodology for 1,2-RF/Y-difunctionalization of conjugated alkenes is reported. Diverse functionalized carbon radicals (RF•), which are generated through copper(I)-initiated selective halogen atom abstraction via a tert-butyl hydroperoxide-induced α-amino radical process, undergo regiocontrolled addition to carbon–carbon double bonds. The newly formed combine with Y = CN, N3, or NCS from TMSY in copper(I)-promoted process form broad spectrum α-cyano-, α-azido-, and...

Proteomic analyses were done on 2 chemosensory appendages of the lone star tick, Amblyomma americanum. Proteins in fore tarsi, which contain olfactory Haller's organ, and palps, that include gustatory sensilla, compared with proteins third tarsi. Also, male female ticks compared. identified by sequence similarity to known proteins, 3-dimensional homology modeling. data also organ-specific transcriptomes from tick Rhipicephalus microplus. The tarsi express a lipocalin not found or palps....

Cysteamine dioxygenase (ADO) has been reported to exhibit two distinct biological functions with a nonheme iron center. It catalyzes oxidation of both cysteamine in sulfur metabolism and N-terminal cysteine-containing proteins or peptides, such as regulator G protein signaling 5 (RGS5). thereby preserves oxygen homeostasis variety physiological processes. However, little is known about its catalytic center how it interacts these types primary substrates addition O2. Here, using electron...

Dynamics of bovine hemoglobin assembly was investigated by monitoring monomers/oligomers equilibria in solution with electrospray ionization mass spectrometry and circular dichroism spectroscopy. Intensities ionic signals corresponding to various protein species (tetramers, dimers, heme-deficient as well apo- holo-monomers) were used estimate relative fractions these a function pH. The fraction folded for each observed estimated based on charge-state distributions the spectra. cumulative...

The anomalous stability of magic-number metal clusters has been associated with closed geometric and electronic shells the opening HOMO–LUMO gaps. Despite this enhanced stability, are known to decay react in condensed phase form other products. Improving our understanding their mechanisms developing strategies control or eliminate cluster instability is a priority, develop more complete theory avoid studying mixtures produced by purified materials, enable technology development. Silver...

Experimental and theoretical evidence reveals the resilience stability of larger aqueous gold clusters protected with p-mercaptobenzoic acid ligands (pMBA) composition Aun(pMBA)p or (n, p). The Au144(pMBA)60, (144, 60), gold-144 cluster is considered special because its high symmetry, abundance, icosahedral structure as well many potential uses in material biological sciences. Yet, to this date, direct confirmation precise total remains elusive. Results presented here from characterization...

M4Ag44(p-MBA)30 molecular nanoparticles, where M is an alkali metal, have recently been shown to exceptional stability, which confers unique traits this molecule. In particular, the synthesis straightforward, produces a truly single-sized product, and has quantitative yield. Here we describe in detail results of experimental theoretical studies on synthesis, structure, electronic optical properties M4Ag44(p-MBA)30, including ESI-MS, NMR, absorption, IR, TGA, other measurements as well DFT...

Although silver nanoparticles are of great fundamental and practical interest, only one structure has been determined thus far: M4Ag44(SPh)30, where M is a monocation, SPh an aromatic thiolate ligand. This in part due to the fact that no other molecular have synthesized with ligands. Here we report synthesis M3Ag17(4-tert-butylbenzene-thiol)12, which good stability unusual optical spectrum. We also present rational strategy for predicting this molecule. First-principles calculations support...

Abstract Cysteamine dioxygenase (ADO) is a thiol whose study has been stagnated by the ambiguity as to whether or not it possesses an anticipated protein‐derived cofactor. Reported herein discovery and elucidation of Cys‐Tyr cofactor in human ADO, crosslinked between Cys220 Tyr222 through thioether (C−S) bond. By genetically incorporating unnatural amino acid, 3,5‐difluoro‐tyrosine (F 2 ‐Tyr), specifically into autocatalytic oxidative carbon–fluorine bond activation fluoride release were...

Gold nanoclusters (AuNCs) with well-defined structure and arrangement possess particular physical functional properties. AuNCs that differ only by less than 1 nm in diameter corresponding to one atomic layer show different structural, optical, physicochemical properties a size-dependent mode, making their analytical characterization challenge. Herein we describe an integrative approach of larger aqueous AuNC (Au102-pMBA44, Au144pMBA60 higher) selected gel electrophoresis (PAGE). We employ...

Heme-based tryptophan dioxygenases are established immunosuppressive metalloproteins with significant biomedical interest. Here, we synthesized two mechanistic probes to specifically test if the α-amino group of substrate directly participates in a critical step O atom transfer during catalysis human 2,3-dioxygenase (TDO). Substitution nitrogen carbon (probe 1) or oxygen 2) slowed catalytic following first such that transferring second becomes less likely occur, although dioxygenated...

LmbB2 is a peroxygenase-like enzyme that hydroxylates l-tyrosine to l-3,4-dihydroxyphenylalanine (DOPA) in the presence of hydrogen peroxide. However, its heme cofactor ligated by proximal histidine, not cysteine. We show can oxidize analogues with ring-deactivated substituents such as 3-nitro-, 3-fluoro-, 3-chloro-, and 3-iodo-l-tyrosine. also found 4-hydroxyl group substrate essential for reacting heme-based oxidant activating aromatic C–H bond. The most interesting observation this study...

An unprecedented AgI -catalyzed efficient method for the coupling of imino ethers and enol diazoacetates through a [3+2]-cycloaddition/C-O bond cleavage/[1,5]-proton transfer cascade process is reported. The general class that includes oxazolines, benzoxazoles benzimidates are applicable substrates these reactions provide direct access to fully substituted pyrroles with uniformly high chemo- regioselectivity. High variability in substitution at pyrrole 2-, 5- N-positions characterizes this...

Metal-free electrophile addition to vinyl diazo compounds reveals highly selective formal [3 + 2] cyclization, 1,2-difunctionalization of alkenes, and C–H functionalization. The success these methodologies is based on electrophilic the vinylogous position compounds, forming diazonium ion intermediates. By using diverse reagents, reactive intermediates show reactivities, affording β-benzohydrofuran-, β-methoxy-β-benzyl-, γ-aminoallyl-substituted α-diazo esters in high yields selectivities....

Galactose oxidase (GAO) contains a Cu(II)-ligand radical cofactor. The cofactor, which is autocatalytically generated through the oxidation of copper, consists cysteine-tyrosine (Cys-Tyr•) as copper ligand. formation cross-linked thioether bond accompanied by C–H scission on Tyr272 with few details known thus far. Here, we report genetic incorporation 3,5-dichlorotyrosine (Cl2-Tyr) and 3,5-difluorotyrosine (F2-Tyr) to replace in GAOV previously optimized for expression directed evolution....

Herein we disclose methods that greatly improve the solution- and gas-phase handling properties of larger aqueous-phase gold–thiolate clusters, which previously presented extreme technical obstacles to molecular analysis size control, even as they have enjoyed ever-wider applications in materials science biomedicine. The are based upon an analogy between polyacidic surface structure pMBA-protected clusters (pMBA = p-mercaptobenzoic acid) oligonucleotides. A volatile ion-pairing reagent, TEA...

Abstract Proteins in the venom of fire ant Solenopsis invicta have been suggested to function pheromone binding. Venom from queens and workers contains different isoforms these proteins, consistent with differing pheromones they secrete, but questions remain about protein composition glandular source. We found that queen a previously uncharacterized pheromone‐binding paralogue known as Sol i 2X1. Using imaging mass spectrometry, we located main proteins poison sac, implying might compete...