Simultaneous cyclization and derivatization of peptides using cyclopentenediones

Unprotected linear peptides containing N-terminal cysteines and another cysteine residue can be simultaneously cyclized and derivatized using 2,2-disubstituted cyclopentenediones. High yields of cyclic peptide conjugates may be obtained in short reaction times using only a slight excess of the cyclopentenedione moiety under TEMPO catalysis and in the presence of LiCl

Exploiting protected maleimides to modify oligonucleotides, peptides and peptide nucleic acids

This manuscript reviews the possibilities offered by 2,5-dimethylfuran-protected maleimides. Suitably derivatized building blocks incorporating the exo Diels-Alder cycloadduct can be introduced at any position of oligonucleotides, peptide nucleic acids, peptides and peptoids, making use of standard solid-phase procedures. Maleimide deprotection takes place upon heating, which can be followed by either Michael-type or Diels-Alder click conjugation reactions. However, the one-pot procedure in which maleimide deprotection and conjugation are simultaneously carried out provides the target conjugate more quickly and, more importantly, in better yield. This procedure is compatible with conjugates involving oligonucleotides, peptides and peptide nucleic acids. A variety of cyclic peptides and oligonucleotides can be obtained from peptide and oligonucleotide precursors incorporating protected maleimides and thiols

Simultaneous cyclization and derivatization of peptides using cyclopentenediones

Unprotected linear peptides containing N-terminal cysteines and another cysteine residue can be simultaneously cyclized and derivatized using 2,2-disubstituted cyclopentenediones. High yields of cyclic peptide conjugates may be obtained in short reaction times using only a slight excess of the cyclopentenedione moiety under TEMPO catalysis and in the presence of LiCl

Selective derivatization of N-terminal cysteines using cyclopentenediones

The outcome of the Michael-type reaction between thiols and 2,2-disubstituted cyclopentenediones varies depending on the thiol. Stable compounds with two fused rings were formed upon reaction with 1,2-aminothiols (such as N-terminal cysteines in peptides). Other thiols gave reversibly Michael-type adducts that were in equilibrium with the starting materials. This differential reactivity allows differently placed cysteines to be distinguished and has been exploited to prepare bioconjugates incorporating two or three different moieties

Raman LIDARs for the atmospheric calibrationalong the line-of-sight of CTA

The Cherenkov Telescope Array (CTA) is the next generation ground-based observatory forgamma-ray astronomy at very-high energies. Employing more than 100 Imaging AtmosphericCherenkov Telescopes in the northern and southern hemispheres, it was designed to reach un-precedented sensitivity and energy resolution. Understanding and correcting for systematic bi-ases on the absolute energy scale and instrument response functions will be a crucial issue forthe performance of CTA. The LUPM group and the Spanish/Italian/Slovenian collaboration arecurrently building two Raman LIDAR prototypes for the online atmospheric calibration alongthe line-of-sight of the CTA. Requirements for such a solution include the ability to characterizeaerosol extinction at two wavelengths to distances of 30 km with an accuracy better than 5%,within time scales of about a minute, steering capabilities and close interaction with the CTAarray control and data acquisition system as well as other auxiliary instruments. Our Raman LI-DARs have design features that make them different from those used in atmospheric science andare characterized by large collecting mirrors (∼2.5 m2), liquid light-guides that collect the light atthe focal plane and transport it to the readout system, reduced acquisition time and highly preciseRaman spectrometers. The Raman LIDARs will participate in a cross-calibration and character-ization campaign of the atmosphere at the CTA North site at La Palma, together with other sitecharacterization instruments. After a one-year test period there, an in-depth evaluation of the so-lutions adopted by the two projects will lead to a final Raman LIDAR design proposal for bothCTA sites

Quantum walks: a comprehensive review

Quantum walks, the quantum mechanical counterpart of classical random walks, is an advanced tool for building quantum algorithms that has been recently shown to constitute a universal model of quantum computation. Quantum walks is now a solid field of research of quantum computation full of exciting open problems for physicists, computer scientists, mathematicians and engineers. In this paper we review theoretical advances on the foundations of both discrete- and continuous-time quantum walks, together with the role that randomness plays in quantum walks, the connections between the mathematical models of coined discrete quantum walks and continuous quantum walks, the quantumness of quantum walks, a summary of papers published on discrete quantum walks and entanglement as well as a succinct review of experimental proposals and realizations of discrete-time quantum walks. Furthermore, we have reviewed several algorithms based on both discrete- and continuous-time quantum walks as well as a most important result: the computational universality of both continuous- and discrete- time quantum walks.Comment: Paper accepted for publication in Quantum Information Processing Journa

Physiologically relevant reconstitution of iron-sulfur cluster biosynthesis uncovers persulfide- processing functions of ferredoxin-2 and frataxin

Iron-sulfur (Fe-S) clusters are essential protein cofactors whose biosynthetic defects lead to severe diseases among which is Friedreich's ataxia caused by impaired expression of frataxin (FXN). Fe-S clusters are biosynthesized on the scaffold protein ISCU, with cysteine desulfurase NFS1 providing sulfur as persulfide and ferredoxin FDX2 supplying electrons, in a process stimulated by FXN but not clearly understood. Here, we report the breakdown of this process, made possible by removing a zinc ion in ISCU that hinders iron insertion and promotes non-physiological Fe-S cluster synthesis from free sulfide in vitro. By binding zinc-free ISCU, iron drives persulfide uptake from NFS1 and allows persulfide reduction into sulfide by FDX2, thereby coordinating sulfide production with its availability to generate Fe-S clusters. FXN stimulates the whole process by accelerating persulfide transfer. We propose that this reconstitution recapitulates physiological conditions which provides a model for Fe-S cluster biosynthesis, clarifies the roles of FDX2 and FXN and may help develop Friedreich's ataxia therapies

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]