This paper presents a comparison of surface morphology obtained after machining Inconel 718 by the conventional insert, by Wiper insert and by using the cutting insert made by Spark Plasma Sintering (SPS). The shape of the special insert was obtained by employing Wire Electrical Discharge Machining (WEDM). The paper focuses on the description of surface topography after turning in dry and wet conditions.
View Article and Find Full Text PDFThis piece of work deals with the influence assessment of the kind of coating of the cutting inserts and their wear on the dimensional accuracy and the top layer microstructure and roughness of the surface machined with constant cutting parameters = 85 m/min, = 0.14 mm/obr and = 0.2 mm.
View Article and Find Full Text PDFThe technology of producing threads, especially in materials that are difficult to cut, is a rare subject of research and scientific publications. The requirements for the production of these elements apply not only to the geometry, but also to the quality of the surface obtained. This is particularly important in the aviation industry, where the durability of the threaded connection affects passenger safety.
View Article and Find Full Text PDFThis article analyzes the results of testing the subgrade and the lower layers of the pavement structure with the light weight deflectometer at a load of 0.1 and 0.15 MPa.
View Article and Find Full Text PDFThis paper presents the results of investigation that was performed on shafts composed of Inconel 718. Tests were performed in dry and wet conditions. Cutting parameters, such as feed and depth of cut, were constant.
View Article and Find Full Text PDFAlterations in metabolic pathways were recently recognized as potential underlying drivers of idiopathic pulmonary fibrosis (IPF), translating into novel therapeutic targets. However, knowledge of metabolic and lipid regulation in fibrotic lungs is limited. To comprehensively characterize metabolic perturbations in the bleomycin mouse model of IPF, we analyzed the metabolome and lipidome by mass spectrometry.
View Article and Find Full Text PDFNonalcoholic steatohepatitis (NASH) is a major cause of liver fibrosis with increasing prevalence worldwide. Currently there are no approved drugs available. The development of new therapies is difficult as diagnosis and staging requires biopsies.
View Article and Find Full Text PDFResearch on ribosomally synthesized and posttranslationally modified peptides (RiPPs) has led to an increasing understanding of biosynthetic mechanisms, mostly drawn from bacterial examples. In contrast, reports on RiPPs from fungal producers, apart from the amanitins and phalloidins, are still scarce. The fungal cyclopeptide omphalotin A carries multiple N-methylations on the peptide backbone, a modification previously known only from nonribosomal peptides.
View Article and Find Full Text PDFLanthipeptides are ribosomally synthesized peptides which undergo extensive post-translational modifications. In addition to novel structural features and bioactivities, the in vitro study on the biosynthesis of the class III lanthipeptide labyrinthopeptin revealed a unique C- to N-terminal directionality of biosynthetic processing. The recently described class III lanthipeptide curvopeptin allowed investigating the directionality aspect in much greater detail: Structural characterization of nine curvopeptin biosynthesis intermediates by high-resolution mass spectrometry combined with a deuterium-labeling approach enabled for the first time building a comprehensive biosynthesis model featuring all three post-translational modification reactions: phosphorylation, elimination, and cyclization.
View Article and Find Full Text PDFLanthipeptides represent an important group of ribosomally synthesized and post-translationally modified peptides (RiPPs). Commonly, in the last steps of their maturation, a part of the peptide, termed the leader, is removed, providing the active compound. This contribution describes for the first time the identification of a protease involved in the removal of the leader peptide of a class III lanthipeptide.
View Article and Find Full Text PDFLabyrinthopeptins are class III lantibiotics produced by the actinomycete Actinomadura namibiensis. The most characteristic structural feature is the posttranslationally installed triamino triacid labionin with a quaternary α-carbon. In addition to the unique structure, labyrinthopeptin A2 possess remarkable antiviral and antiallodynic biological activities.
View Article and Find Full Text PDFLantibiotics are ribosomally synthesized peptides containing post-translationally installed lanthionine thioether bridges. Recently characterized class III lantibiotics have also revealed the occurrence of labionin, a novel carbacyclic variation of lanthionine, and highlighted the structural diversity within this group. Here we describe the discovery and characterization of curvopeptins produced by Thermomonospora curvata, the first class III lantibiotics of thermophilic origin.
View Article and Find Full Text PDFThe biosynthesis of a considerable number of ribosomally synthesized peptide antibiotics involves the modification of Ser and Thr residues of a precursor peptide. This post-translational processing is performed by one or multiple modifying enzymes encoded in the biosynthetic gene cluster. We present a deuterium-label based enzyme assay, utilizing a series of peptide substrates with α-deuterated Ser, for the determination of the dehydration order during the biosynthesis of class III lantibiotic labyrinthopeptin A2.
View Article and Find Full Text PDFLantibiotics are a large group of ribosomally synthesized peptides post-translationally modified to incorporate the amino acid lanthionine. They are classified, according to their biosynthetic pathway and bioactivity, into three major subtypes. Of Actinomycetes type III lantibiotics, only four peptides (SapB, SapT, LabA1, and LabA2) have been described and structurally characterized, although homologous gene clusters are abundant in other Actinomycetes.
View Article and Find Full Text PDFLantibiotics are peptide antibiotics, realizing their unique secondary structure by posttranslational modifications, the most important one being the formation of the characteristic amino acid lanthionine. Like other ribosomal peptide antibiotics, they are synthesized with an N-terminal leader peptide important for posttranslational processing by modifying enzymes; after peptide maturation, the leader peptide is proteolytically cleaved off. Numerous studies of the leader peptides of class I and II lantibiotics already showed their crucial role in recognition, self-immunity, and extracellular transport.
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