Chromatographically homogeneous egg white lysozyme has been subjected under reduced pressure to 0.67-m.e.v. y-rays. At 37% destruction of enzymic activity, three inactive aggregates and one partially active fraction have been isolated by salt precipitation and chromatographic procedures. The aggregates, upon reduction with 2-mercaptoethanol and reaction with iodoacetic acid, give derivatives wi...

EGFR, HER2, and HER3 contribute to the initiation and progression of human cancers, and are therapeutic targets for monoclonal antibodies and tyrosine kinase inhibitors. An important source of resistance to these agents arises from functional redundancy among EGFR, HER2, and HER3. EGFR family members contain conserved extracellular structures that are stabilized by disulfide bonds. Compounds th...

The Dsb protein family is responsible for introducing disulfide bonds into nascent proteins in prokaryotes, stabilizing the structure of many proteins. Helicobacter pylori HP0231 is a Dsb-like protein, shown to catalyze disulfide bond formation and to participate in redox homeostasis. Notably, many H. pylori virulence factors are stabilized by the formation of disulfide bonds. By employing H. p...

In recent years an increasing number of miniproteins containing an amide-cyclized backbone have been discovered. The cyclotide family is the largest group of such proteins and is characterized by a circular protein backbone and six conserved cysteine residues linked by disulfide bonds in a tight core of the molecule. These form a cystine knot in which an embedded ring formed by two of the disul...

Dithiothreitol (DTT) is the standard reagent for reducing disulfide bonds between and within biological molecules. At neutral pH, however, >99% of DTT thiol groups are protonated and thus unreactive. Herein, we report on (2S)-2-amino-1,4-dimercaptobutane (dithiobutylamine or DTBA), a dithiol that can be synthesized from l-aspartic acid in a few high-yielding steps that are amenable to a large-s...

We describe a mutation (dsbA) that renders Escherichia coli severely defective in disulfide bond formation. In dsbA mutant cells, pulse-labeled beta-lactamase, alkaline phosphatase, and OmpA are secreted but largely lack disulfide bonds. These disulfideless proteins may represent in vivo folding intermediates, since they are protease sensitive and chase slowly into stable oxidized forms. The ds...