Deciphering the Path of S-nitrosation of Human Thioredoxin: Evidence of an Internal NO Transfer and Implication for the Cellular Responses to NO.

Nitric oxide (NO) is a free radical with a signaling capacity. Its cellular functions are achieved mainly through S-nitrosation where thioredoxin (hTrx) is pivotal in the S-transnitrosation to specific cellular targets. In this study, we use NMR spectroscopy and mass spectrometry to follow the mechanism of S-(trans)nitrosation of hTrx. We describe a site-specific path for S-nitrosation by measuring the reactivity of each of the 5 cysteines of hTrx using cysteine mutants. We showed the interdependence of the three cysteines in the nitrosative site. C73 is the most reactive and is responsible for all S-transnitrosation to other cellular targets. We observed NO internal transfers leading to C62 S-nitrosation, which serves as a storage site for NO. C69-SNO only forms under nitrosative stress, leading to hTrx nuclear translocation.

Comparison of mono-rhamnolipids and di-rhamnolipids on microbial enhanced oil recovery (MEOR) applications.

Rhamnolipids (RMLs) have more effectiveness for specific uses according to their homologue proportions. Thus, the novelty of this work was to compare mono-RMLs and di-RMLs physicochemical properties on microbial enhanced oil recovery (MEOR) applications. For this, RML produced by three strains of Pseudomonas aeruginosa containing different homologues proportion were used: a mainly mono-RMLs producer (mono-RMLs); a mainly di-RMLs producer (di-RMLs), and the other one that produces relatively balanced amounts of mono-RML and di-RML homologues (mono/di-RML). For mono-RML, the most abundant molecules were Rha-C10 C10 (m/z 503.3), for di-RML were RhaRha-C10 C10 (m/z 649.4) and for Mono/di-RML were Rha-C10 C10 (m/z 503.3) and RhaRha-C10 C10 (m/z 649.4). All RMLs types presented robustness under high temperature and variation of salinity and pH, and high ability for oil displacement, foam stability, wettability reversal and were classified as safe for environment according to the European Union Directive No. 67/548/EEC. For all these properties, it was observed a highlight for mono-RML. Mono-RML presented the lowest surface tension (26.40 mN/m), interfacial tension (1.14 mN/m), and critical micellar concentration (CMC 27.04 mg/L), the highest emulsification index (EI24 100%) and the best wettability reversal (100% with 25 ppm). In addition, mono-RML showed the best acute toxicity value (454 mg/L), making its application potential even more attractive. Based on the results, it was concluded that all RMLs homologues studied have potential for MEOR applications. However, results showed that mono-RML stood out and have the best mechanism of oil incorporation in micelles due their most effective surface-active physicochemical features.

An ortho-Iminoquinone Compound Reacts with Lysine Inhibiting Aggregation while Remodeling Mature Amyloid Fibrils.

Protein aggregation is a hallmark of several neurodegenerative diseases, including Alzheimer's and Parkinson's diseases. It has been shown that lysine residues play a key role in the formation of these aggregates. Thus, the ability to disrupt aggregate formation by covalently modifying lysine residues could lead to the discovery of therapeutically relevant antiamyloidogenesis compounds. Herein, we demonstrate that an ortho-iminoquinone (IQ) can be utilized to inhibit amyloid aggregation. Using alpha-synuclein and Aß1-40 as model amyloidogenic proteins, we observed that IQ was able to react with lysine residues and reduce amyloid aggregation. We also observed that IQ reacted with free amines within the amyloid fibrils preventing their dissociation and seeding capacity.