Wynberg's report from 1977 that natural cinchona alkaloids catalyze the asymmetric conjugate addition of aromatic thiols to cycloalkenones is a landmark discovery in hydrogen bonding organocatalysis. Wynberg proposed that this reaction proceeded via the formation of a thiolate-alkylammonium tight ion pair and activation of the enone electrophile by a hydrogen bond from the catalyst's hydroxyl g...

(-)-Chokol A is a fungitoxic modified sesquiterpene isolated from the stromata of timothy grass Phleum prutense infected by the pathogenic fungus Epichloe typhinu. Isolated for the first time in 1985 by Yoshihara et al.C2I, (-)-chokol A and the more active chok01s B, CL3], D and Gl4] have recently received special attention due to their fungitoxic proper tie^[^]. So far, two syntheses for racem...

In this article newly synthesized azide derivative of hemin and DNA-hemin conjugate are characterized. Hemin-azide was purified using HPLC and characterized using elemental analysis, IR and NMR. The DNA-hemin conjugate was obtained via click chemistry [1] and click reaction was carried out using traditional Cu-catalyzed and Cu-free approaches. The final product was successfully obtained using C...

Goat anti-mouse immunoglobulin horseradish peroxidase (HRP) conjugate was diluted in PBS containing 10% BSA. This conjugate has been successfully used from various manufacturers; however, specific lots need to be titrated for optimal performance. One particular preparation of HRPconjugated goat anti-mouse IgG, IgM and IgA (Catalog No. A 0412; Sigma Chemical, St. Louis, MO, USA) was diluted at 1...

Reversal of the multidrug-resistant (MDR) phenotype is very important for chemotherapy success. In fact, the expression of the MDR1 gene-encoded P-glycoprotein (P-gp) actively expels antitumor agents such as daunomycin (DNM) out of the cells, resulting in drug resistance. We show that upon conjugation to triplex-forming oligonucleotides, it is possible to address DNM in resistant cells (MCF7-R ...

A method of cysteine alkylation using cyclopropenyl ketones is described. Due to the significant release of cyclopropene strain energy, reactions of thiols with cyclopropenyl ketones are both fast and irreversible and give rise to stable conjugate addition adducts. The resulting cyclopropenyl ketones have a low molecular weight and allow for simple attachment of amides via N-hydroxysuccinimide ...

The development and optimization of a palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enone conjugate acceptors is described. These reactions employ air-stable and readily-available reagents in an operationally simple and robust transformation that yields β-quaternary ketones in high yields and enantioselectivities. Notably, the reaction itself is highly toleran...

A heterogeneous microplate enzyme immunoassay with a sensitivity of 10 pg/ml (1 pg/assay) toward gentamicin has been developed for the detection of aminoglycoside antibiotics in fermentation broths. Purified gentamicin antibody was coated onto the surface of the wells of microtiter plates and incubated with gentamicin-alkaline phosphatase conjugate. The amount of enzyme bound to the antibody wa...