Plasma plasminogen is the precursor of the tumor angiogenesis inhibitor, angiostatin. Generation of angiostatin in blood involves activation of plasminogen to the serine protease plasmin and facilitated cleavage of two disulfide bonds and up to three peptide bonds in the kringle 5 domain of the protein. The mechanism of reduction of the two allosteric disulfides has been explored in this study....

This review summarizes recent developments in photocatalyzed carbon-sulfur bond formation. General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways.

Carbonic anhydrase enzymes catalyse the reversible hydration of carbon dioxide to bicarbonate. A thermophilic Thermovibrio ammonificans α-carbonic anhydrase (TaCA) has been expressed in Escherichia coli and structurally and biochemically characterized. The crystal structure of TaCA has been determined in its native form and in two complexes with bound inhibitors. The tetrameric enzyme is stabil...

Thioredoxin from Escherichia coli was shown to catalyze the reduction of insulin disulfides by dithiothreitol. A quantitative assay was developed which measures the rate of insulin reduction spectrophotometrically at 650 nm as turbidity formation from the precipitation of the free insulin B chain. Thioredoxin, at 5 microM concentration, accelerated the reaction between 0.130 mM insulin and 1.0 ...

icrotubule plus ends may control sites of cell polarity and cytokinesis in both animal and yeast cells, but the mechanisms behind this have remained obscure. have detected a protein complex in Schizosaccharomyces pombe that links the actin-and microtubule-based cytoskeletal systems. Its existence also suggests that microtubule plus ends polarize cells by targeting cell-polarity factors to the c...

In prokaryotes, disulfides are generated by the DsbA-DsbB system. DsbB functions to generate disulfides by quinone reduction. These disulfides are passed to the DsbA protein and then to folding proteins. To investigate the DsbA-DsbB catalytic system, we performed an in vivo selection for chromosomal dsbA and dsbB mutants. We rediscovered many residues previously shown to be important for the ac...

Dormant spores of Bacillus megaterium were found to contain approximately 850 pmol of coenzyme A (CoA) per milligram of dry weight. Of this total, less than 1.5% was acetyl-CoA, 25% was CoA-disulfide, 43% was in disulfide linkage to protein, and the remainder was the free thiol. Dormand spores of Bacillus cereus and Clostridium bifermentans contained 700 and 600 pmol of CoA per milligram of dry...

Chemisorption of alkanethiols, RSH, or dialkyl disulfides, RSSR, on gold gives ordered monolayers-l-S SAMs (self-assembled monolayers) formed from either precursor are believed to comprise the sattte species on the gold surface-gold(I) alkyl thiolate (RS-Aus+ on these predominately Au(111) surfaces) adsorbed epitaxially on the gold(0) substrate-but the only direct experimental eviderrce support...

Studies on the mechanism of the glutathione regeneration (Saxena, V.P., and Wetlaufer, D.B. (1970) Biochemistry 9, 5015-5023) of hen egg lysozyme have been carried out. The first two stoichiometric disulfides in lysozyme are formed about 8 times more rapidly than the second two. Almost no enzymic activity is regained until the first two disulfides are formed, thus ruling out an all-or-none mech...

Stabilization of protein tertiary structure by disulfides can interfere with glycosylation of acceptor sites (NXT/S) in nascent polypeptides. Here, we show that MagT1, an ER-localized thioredoxin homologue, is a subunit of the STT3B isoform of the oligosaccharyltransferase (OST). The lumenally oriented active site CVVC motif in MagT1 is required for glycosylation of STT3B-dependent acceptor sit...