For the development of surface-functionalized gold nanoparticles as cellular probes and delivery agents, we have synthesized hetero-bifunctional poly(ethylene glycol) (PEG, MW 1500) having a thiol group on one terminus and a reactive functional group on the other for use as a flexible spacer. Coumarin, a model fluorescent dye, was conjugated to one end of the PEG spacer and gold nanoparticles w...

A convenient, versatile and straightforward synthesis of a novel heterotrifunctional peptide-based linker molecule is described. This generic bio-labelling reagent contains an amine-reactive N-hydroxysuccinimidyl carbamate moiety, an aldehyde/ketone-reactive aminooxy group and a thiol group with a propensity to form urea, oxime and thioether linkages respectively. The full chemical orthogonalit...

Polyethylene glycol (PEG) conjugation technology has been successfully applied to improve the performance of protein drugs. In this study, L-asparaginase was N-terminal site-specifically modified by alkylating PEG with monomethoxy polyethylene glycol-propionaldehyde (mPEG-ALD20000). The optimum reaction parameters were determined as pH 5.0, a molar ratio of mPEG-ALD2000 to L-asparaginase of 10:...

Three aryl methyl sulfoxides were prepared via the following sequence: synthesis of menthyl arenesulfenate from corresponding thiol, diastereoselective oxidation leading to sulfinate, then reaction with a Grignard reagent. The moiety was substituted ester on ortho position or nitro group para position. sulfenate esters obtained in fair excellent yield (42–82%). Four different oxidizing agents t...

The reactivities of the two cysteine thiol groups of calf thymus F3 histone were investigated using 5,5'-dithiobis-[2- nitrobenzoic acid], (DTNB). In isolated histone, both thiol groups were available for reaction. However, analysis of reaction profiles of native deoxyribonucleohistone, (DNH), in various solvent conditions, together with gel electrophoresis studies of DNH modified with DTNB, sh...

The synthesis of long-arm thiolated beads from beaded polyacrylamide ( $400 mesh, 10-37^ M diameter, 2,000 Dalton inclusion limit) is described. The long spacer arm, polyethylene glycol di(3-mercapto-propionate)(PEG-DMP) was i introduced via thioether formation with haloacetamidoethyl beads. The latter were prepared via the N-hydroxysuccinimide ester (NHS) after surveying a number of peptide co...

Thiolation of immunoglobulin G (IgG) with DL-N-acetylhomocysteinethiolactone, catalyzed by 2-pyridinealdoxime methiodide, incorporated new sulfur groups into IgG. Triaziquinone was subsequently conjugated to the sulfur groups. Triaziquinone-IgG complex retained the alkylating activity of the drug and the immunological activity of the antibody. The conjugation procedure was inhibited by the thio...

A bifunctional fluorescent alkylating agent, dibromobimane, has been used to stabilize a preexisting primary loop in myosin subfragment 1 (S-1). The crosslink achieved joins Cys-707 (called sulfhydryl group "SH1") of the 20-kDa domain (formerly called "20K" domain) with a thiol of the 50-kDa domain and seems to place the dibromobimane near the ATP-perturbable tryptophan.