One-Pot Cyclization and Cleavage of Peptides with N-Terminal Cysteine via the N,S-Acyl Shift of the N-2-[Thioethyl]glycine Residue.

We developed a one-pot method for peptide cleavage from a solid support via the N,S-acyl shift of N-2-[thioethyl]glycine and transthioesterification using external thiols to produce cyclic peptides through native chemical self-ligation with the N-terminal cysteine. The feasibility of this methodology is validated by the syntheses of model short peptides, including a tetrapeptide, the bicyclic sunflower trypsin inhibitor SFTI-1, and rhesus Θ-defensin RTD-1. Synthesis of the whole peptide precursor can be fully automated and proceeds without epimerization or dimerization.

Application of Safirinium N-Hydroxysuccinimide Esters to Derivatization of Peptides for High-Resolution Mass Spectrometry, Tandem Mass Spectrometry, and Fluorescent Labeling of Bacterial Cells.

Mass spectrometry methods are commonly used in the identification of peptides and biomarkers. Due to a relatively low abundance of proteins in biological samples, there is a need for the development of novel derivatization methods that would improve MS detection limits. Hence, novel fluorescent N-hydroxysuccinimide esters of dihydro-[1,2,4]triazolo[4,3-a]pyridin-2-ium carboxylates (Safirinium P dyes) have been synthesized. The obtained compounds, which incorporate quaternary ammonium salt moieties, easily react with aliphatic amine groups of peptides, both in solution and on the solid support; thus, they can be applied for derivatization as ionization enhancers. Safirinium tagging experiments with ubiquitin hydrolysate revealed that the sequence coverage level was high (ca. 80%), and intensities of signals were enhanced up to 8-fold, which proves the applicability of the proposed tags in the bottom-up approach. The obtained results confirmed that the novel compounds enable the detection of trace amounts of peptides, and fixed positive charge within the tags results in high ionization efficiency. Moreover, Safirinium NHS esters have been utilized as imaging agents for fluorescent labeling and the microscopic visualization of living cells such as E. coli Top10 bacterial strain.

An Optimised Di-Boronate-ChemMatrix Affinity Chromatography to Trap Deoxyfructosylated Peptides as Biomarkers of Glycation.

We report herein a novel ChemMatrix® Rink resin functionalised with two phenylboronate (PhB) moieties linked on the N-α and N-ε amino functions of a lysine residue to specifically capture deoxyfructosylated peptides, compared to differently glycosylated peptides in complex mixtures. The new PhB-Lys(PhB)-ChemMatrix® Rink resin allows for exploitation of the previously demonstrated ability of cis diols to form phenylboronic esters. The optimised capturing and cleavage procedure from the novel functionalised resin showed that only the peptides containing deoxyfructosyl-lysine moieties can be efficiently and specifically detected by HR-MS and MS/MS experiments. We also investigated the high-selective affinity to deoxyfructosylated peptides in an ad hoc mixture containing unique synthetic non-modified peptides and in the hydrolysates of human and bovine serum albumin as complex peptide mixtures. We demonstrated that the deoxyfructopyranosyl moiety on lysine residues is crucial in the capturing reaction. Therefore, the novel specifically-designed PhB-Lys(PhB)-ChemMatrix® Rink resin, which has the highest affinity to deoxyfructosylated peptides, is a candidate to quantitatively separate early glycation peptides from complex mixtures to investigate their role in diabetes complications in the clinics.

Attempting to synthesize lasso peptides using high pressure.

Lasso peptides are unique in that the tail of the lasso peptide threads through its macrolactam ring. The unusual structure and biological activity of lasso peptides have generated increased interest from the scientific community in recent years. Because of this, many new types of lasso peptides have been discovered. These peptides can be synthesized by microorganisms efficiently, and yet, their chemical assembly is challenging. Herein, we investigated the possibility of high pressure inducing the cyclization of linear precursors of lasso peptides. Unlike other molecules like rotaxanes which mechanically interlock at high pressure, the threaded lasso peptides did not form, even at pressures the high pressure up to 14 000 kbar.

[Proinflammatory cytokines in cardiovascular diseases as potential therapeutic target]. / Cytokiny prozapalne w chorobach ukladu krazenia jako potencjalny cel terapeutyczny.

Several lines of evidence suggest that inflammation plays a pathogenic role in the development and progression of congestive heart failure, influencing heart contractility and hypertrophy, promoting apoptosis, and contributing to the myocardial remodeling process. Proinflammatory cytokines are important mediators of immune response, associated with endothelial dysfunction in patients with coronary artery disease or heart failure. The presence, both at tissue level and in the circulation, of increased levels of pro-inflammatory cytokines suggests that immune activation might be a relevant mechanism contributing to cardiac as well as peripheral manifestations of the disease. Traditional cardiovascular drugs have little influence on the cytokine network. Results from randomized, placebo controlled anti-TNF studies suggest lack of effect of such therapy, but the concept of immune modulation is still intensively studied. In this review we evaluate the diagnostic and prognostic value of the activation of proinflammatory cytokines, theirs role in the pathogenesis of the cardiovascular diseases and the new ways of treatment.

New methods in laboratory diagnostics of dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is a multifactorial heart disease in which there is enlargement and systolic dysfunction of one or both ventricles. The exhaustion of compensatory mechanisms leads to symptoms of congestive heart failure, which is a significant problem in contemporary cardiology. DCM is still diagnosed using clinical assessment; echocardiography is necessary, and in some clinical situations we need hemodynamic assessment in order to identify the etiology and progression of heart disease. These tests are necessary for choice of treatment and qualification for heart transplant. Investigators are looking for new, valuable, additional parameters which could be of use in screening and heart disease progression assessment, and which may be helpful in the management and risk stratification of patients with DCM. These monitoring and prognostic tools in patients with chronic heart failure can be biomarkers, such as natriuretic peptides: BNP and NT-proBNP, cardiac troponins or inflammatory cytokines and their receptors. Moreover, there are ongoing research projects concerning persistently elevated uric acid, Ca-125 and osteopontin concentrations for the identification of patients with DCM, as well as adverse prognoses.

The ventricular assist device: a bridge to ventricular recovery, a bridge to heart transplantation or destination therapy?

Despite advances in pharmacological treatments aimed at a neurohormonal blockade for heart failure, there is still a growing number of patients with advanced symptoms who suffer significant morbidity and mortality. At present the most effective cure for end-stage congestive heart failure is cardiac transplantation. This method is severely limited owing to a lack of available organs. This is why ventricular assist devices (VADs) capable of completely supporting the circulation are taking on an increasingly important role in heart failure therapy. VADs are important bridges to cardiac transplantation. The Randomised Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) trial revealed that they could be used as long-term destination therapy for non-transplant candidates. The latest studies show that VAD support may also function as a bridge to ventricular recovery and enable this procedure to take place. Apart from foreign devices, there is the Polish system (PCAS), which is being prepared for introduction into global practice. (Cardiol J 2007; 14: 14-23).