Noncationic dipeptide mimic oligomers as cell penetrating nonpeptides (CPNP).

Small oligomers of constrained dipeptide mimics have been synthesized as new vectors for intracellular delivery. They are highly internalized by cells and delivered to the lysosomes by an energy-dependent pathway. This new class of vectors referred to as cell penetrating nonpeptides (CPNP) possess the distinctive feature of being noncationic.

Synthesis of C5-tetrazole derivatives of 2-amino-adipic acid displaying NMDA glutamate receptor antagonism.

Five derivatives of 2-amino-adipic acid bearing a tetrazole-substituted in C5 position were synthesized. These compounds displayed selective antagonism towards N-methyl-D: -aspartate (NMDA) receptors compared with AMPA receptors, and they were devoid of any neurotoxicity. Among these five analogues, one exhibited a higher affinity for synaptic NMDA responses than the other four.

[Pharmacological chaperones: a potential therapeutic treatment for conformational diseases].

Many genetic and neurodegenerative diseases in humans result from protein misfolding and/or aggregation. These diseases are named conformational diseases. As a result, the misfolded non functional proteins are rejected and misrouted by the cellular quality control system, and cannot play their endogenous physiological roles.

A new generation of cross-linkers for selective detection by MALDI MS.

We designed a new cross-linker bearing a CHCA moiety. The use of the CHCA-tagged cross-linker JMV 3378 in conjunction with a neutral MALDI matrix alpha-cyano-4-hydroxycinnamic methyl ester enabled specific signal enhancement in MALDI-TOF MS of cross-link containing peptides. Discrimination between modified and non-modified peptides can be achieved by comparison of two spectra, one using CHCA and the other using the alpha-cyano-4-hydroxycinnamic methyl ester matrix.

Comparison of inert supports in laser desorption/ionization mass spectrometry of peptides: pencil lead, porous silica gel, DIOS-chip and NALDI target.

In the search for alternative inert surfaces replacing silicon chips in Desorption/Ionization On porous Silicon (DIOS)-like mass spectrometry analyses, nanostructured silicon-based NALDI chips were evaluated in Laser Desorption/Ionization (LDI) of peptides. Comparisons were made using commercially available DIOS chips (MassPREP-DIOS-target), amorphous carbon powder from lead pencil and porous silica gel used for chromatographic purposes as reference supports. A set of synthetic model peptides presenting variable amino acid sequences of various lengths was analyzed under all conditions.

ROP2 from Toxoplasma gondii: a virulence factor with a protein-kinase fold and no enzymatic activity.

The ROP2 protein and its paralogs are important virulence factors secreted into the host cell by the parasite Toxoplasma gondii. Here we describe the crystal structure of a large and soluble domain of mature ROP2, representative of the ROP2-like protein family. This is a structure of a protein-kinase fold that is devoid of catalytic residues and does not bind ATP.

Comparison of LID versus CID activation modes in tandem mass spectrometry of peptides.

We report our contribution to the systematic investigation of peptide fragmentations performed on high-performance Tof equipment, operating in MS and MS/MS modes, such as ESI-QqTof and MALDI-Tof/Tof instruments that are commonly available today in proteomic laboratories. Whereas the former analyzer's configuration provides low-energy collision-induced dissociations (CID), the latter allows tunable activation methods of the selected parent ion to induce either metastable laser-induced dissociations (LID) or high-energy CID ('gas on spectra LID'). Fragmentation of the monoprotonated ion of 53 peptides (FW 807-2853 g/mol) was undertaken upon low-energy CID on an ESI-QTof mass spectrometer (Waters) as well as high-energy CID and LID conditions on a MALDI Ultraflex mass spectrometer (Bruker).

Solid-phase synthesis of 4-methylcarboxy-1,4-benzodiazepine-2,5-diones.

A solid-phase synthesis of 1,4-benzodiazepinone-2,5-diones is described. This new route can afford benzodiazepinone bearing a N-urethane-protected amine and a carboxylic acid function. This kind of building block is valuable as a dipeptide mimic or beta-turn mimetic, and it can be introduced in place of any amino acid in peptide synthesis.

G protein activation by the leukotriene B4 receptor dimer. Evidence for an absence of trans-activation.

There is compelling evidence that G protein-coupled receptors exist as homo- and heterodimers, but the way these assemblies function at the molecular level remains unclear. We used here the purified leukotriene B(4) receptor BLT1 stabilized in its dimeric state to analyze how a receptor dimer activates G proteins. For this, we produced heterodimers between the wild-type BLT1 and a BLT1/ALXR chimera.

Molecular basis for the lack of enantioselectivity of human 3-phosphoglycerate kinase.

Non-natural L-nucleoside analogues are increasingly used as therapeutic agents to treat cancer and viral infections. To be active, L-nucleosides need to be phosphorylated to their respective triphosphate metabolites. This stepwise phosphorylation relies on human enzymes capable of processing L-nucleoside enantiomers.

Laser desorption/ionization mass spectrometry on porous silica and alumina for peptide mass fingerprinting.

We investigated a variant of desorption/ionization on porous silicon (DIOS) mass spectrometry utilizing an aqueous suspension of either porous silica gel or porous alumina (pore size of 60 and 90 A, respectively). Laser desorption/ionization (LDI) from samples directly deposited on a stainless steel surface without any inorganic substrates was also achieved. Synthetic peptides designed to cover large sequence diversity constituted our model compounds.

A novel role for PA28gamma-proteasome in nuclear speckle organization and SR protein trafficking.

In eukaryotic cells, proteasomes play an essential role in intracellular proteolysis and are involved in the control of most biological processes through regulated degradation of key proteins. Analysis of 20S proteasome localization in human cell lines, using ectopic expression of its CFP-tagged alpha7 subunit, revealed the presence in nuclear foci of a specific and proteolytically active complex made by association of the 20S proteasome with its PA28gamma regulator. Identification of these foci as the nuclear speckles (NS), which are dynamic subnuclear structures enriched in splicing factors (including the SR protein family), prompted us to analyze the role(s) of proteasome-PA28gamma complexes in the NS.

NAD kinases use substrate-assisted catalysis for specific recognition of NAD.

Here we describe the crystal structures of the NAD kinase (LmNADK1) from Listeria monocytogenes in complex with its substrate NAD, its product NADP, or two synthesized NAD mimics. We identified one of the NAD mimics, di-adenosine diphosphate, as a new substrate for LmNADK1, whereas we showed that the closely related compound di-5'-thioadenosine is a novel non-natural inhibitor for this enzyme. These structures suggest a mechanism involving substrate-assisted catalysis.

Common structural requirements for heptahelical domain function in class A and class C G protein-coupled receptors.

G protein-coupled receptors (GPCRs) are key players in cell communication. Several classes of such receptors have been identified. Although all GPCRs possess a heptahelical domain directly activating G proteins, important structural and sequence differences within receptors from different classes suggested distinct activation mechanisms.

2-Trimethylsilylethanesulfonyl (SES) versus tosyl (Ts) protecting group in the preparation of nitrogen-containing five-membered rings. A novel route for the synthesis of substituted pyrrolines and pyrrolidines.

The 2-trimethylsilylethanesulfonyl (or SES) protecting group was compared to the tosyl (Ts) group in the preparation of a nitrogen-containing five-membered ring obtained by the aza-Baylis-Hillman/alkylation/RCM route. While deprotection of Ts-protected pyrrolines gave only pyrroles, deprotection of the same SES-protected compounds gave either pyrroles or free amine pyrrolines depending on the deprotection conditions. The SES-protected pyrrolines were hydrogenated to yield pyrrolidines with an excellent diastereoselectivity.

Sequential aza-Baylis-Hillman/ring closing metathesis/aromatization as a novel route for the synthesis of substituted pyrroles.

A new route to diverse 2-substituted-3-methoxycarbonyl pyrroles has been developed. Diverse SES protected alpha-methylene beta-aminoesters were obtained by a 3-component aza-Baylis-Hillman reaction. Diversity arose from the aryl aldehydes which can be used in this reaction.

Soluble polymer supported synthesis of alpha-amino acid derivatives.

A Schiff base activated glycine supported on a soluble polymer (poly(ethylene glycol) (PEG)) was readily alkylated with a wide variety of electrophiles in the presence of a carbonate base in acetonitrile. The presence of the polymer provided a phase-transfer catalysis environment which accelerated the reaction. Effects of various carbonate bases and leaving groups have been also studied.