We developed a real-time drug-reporting conjugate (CPT-SS-CyN) composed of a near-infrared (NIR) fluorescent cyanine-amine dye (CyN), a disulfide linker, and a model therapeutic drug (camptothecin, CPT). Treatment with dithiothreitol (DTT) induces cleavage of the disulfide bond, followed by two simultaneous intramolecular cyclization reactions with identical kinetics, one to cleave the urethane...

In this work, the main attention was focused on the synthesis of stimuli-responsive magnetic nanoparticles (SR-MNPs) and the influence of glutathione concentration on its cleavage efficiency. Magnetic nanoparticles (MNPs) were first modified with activated pyridyldithio. Then, MNPs modified with activated pyridyldithio (MNPs-PDT) were conjugated with 2, 4-diamino-6-mercaptopyrimidine (DMP) to f...

Cleavage of the disulfide bond linking the heavy and the light chains of tetanus toxin is necessary for its inhibitory action on exocytotic release of catecholamines from permeabilized chromaffin cells [(1989) FEBS Lett. 242, 245-248; (1989) J. Neurochem., in press]. The related botulinum A toxin also consists of a heavy and a light chain linked by a disulfide bond. The actions of both neurotox...

During endoplasmic reticulum (ER)-associated degradation (ERAD), terminally misfolded proteins are retrotranslocated from the ER to the cytosol and degraded by the ubiquitin-proteasome system. Misfolded glycoproteins are recognized by calnexin and transferred to EDEM1, followed by the ER disulfide reductase ERdj5 and the BiP complex. The mechanisms involved in ERAD of nonglycoproteins, however,...

Soluble CD21 (sCD21), released from the plasma membrane by proteolytic cleavage (shedding) of its extracellular domain (ectodomain) blocks B cell/follicular dendritic cell interaction and activates monocytes. We show here that both serine- and metalloproteases are involved in CD21 shedding. Using the oxidant pervanadate to mimic B cell receptor activation and thiol antioxidants such as N-acetyl...

Ion dissociation is the usual basis for tandem MS analysis but a significant limitation is that only charged fragments from ion dissociation events are detected while neutral fragments are simply lost. This study reports our continued effort to solve this problem by developing atmospheric pressure neutral reionization mass spectrometry (APNR). In APNR, analyte ions are thermally dissociated (at...

GARP is a transmembrane protein present on stimulated human regulatory T lymphocytes (Tregs), but not on other T lymphocytes (Th cells). It presents the latent form of TGF-β1 on the Treg surface. We report here that GARP favors the cleavage of the pro-TGF-β1 precursor and increases the amount of secreted latent TGF-β1. Stimulated Tregs, which naturally express GARP, and Th cells transfected wit...

Single-molecule force-clamp spectroscopy offers a novel platform for mechanically denaturing proteins by applying a constant force to a polyprotein. A powerful emerging application of the technique is that, by introducing a disulfide bond in each protein module, the chemical kinetics of disulfide bond cleavage under different stretching forces can be probed at the single-bond level. Even at for...

A detailed investigation of the self-assembled monolayers of diphenyl disulfide (DDS), diphenyl diselenide (DDSe), and naphthalene disulfide (NDS) on polycrystalline gold films using surface-enhanced Raman spectroscopy (SERS), X-ray photoelectron spectroscopy (XPS), and electrochemistry is presented. Whereas DDS dissociatively chemisorbs on Au, in both DDSe and NDS, the Se-Se and S-S bonds, res...