The solution structure of termicin from hemocytes of the termite Pseudacanthotermes spiniger was determined by proton two-dimensional nuclear magnetic resonance spectroscopy and molecular modeling techniques. Termicin is a cysteine-rich antifungal peptide also exhibiting a weak antibacterial activity. The global fold of termicin consists of an α-helical segment (Phe4–Gln14) and a two-stranded (Phe19–Asp25 and Gln28–Phe33) antiparallel β-sheet forming a 'cysteine stabilized αβ motif' (CSαβ) also found in antibacterial and antifungal defensins from insects and from plants. Interestingly, termicin shares more structural similarities with the antibacterial insect defensins and with MGD-1, a mussel defensin, than with the insect antifungal defensins such as drosomycin and heliomicin. These structural comparisons suggest that global fold alone does not explain the difference between antifungals and antibacterials. The antifungal properties of termicin may be related to its marked hydrophobicity and its amphipatic structure as compared to the antibacterial defensins. [SWISS-PROT accession number: Termicin (); PDB accession number: 1MM0.]. Efficient host defense mechanisms are required to counteract the microbial challenges to which living organisms are exposed. In higher vertebrates, there are two types of immunities: innate or natural immunity, and acquired or adaptive immunity. Subtract out the inner part of the shape. • Make sure the shape 1 layer is selected, change the opacity value so the overlaying image you just created is transparent, I suggest a value of around 30% • The third picture is showing what the change should look like from 100% opacity to 30% • Note: Also I changed my color back to black from white so I could have more contrast as I was working. • Next make sure that the shape 1 layer is selected in the layers window, and click the subtract from shape area button on the top tool bar (this is the button that almost resembles a Tetris piece) • Repeat steps 1 through 3 for the inside of the background images black outline as shown in the last picture. Change the layer opacity • Direct your attention to the layers window, as shown in the fourth picture, which should be located in the lower right hand corner of the screen. Custom shapes for photoshop elements. • Doing this will allow us to see the other features of the background image that we want to trace. In contrast, invertebrates and plants defend themselves against pathogens exclusively through mechanisms that are part of innate immunity. Innate immunity is triggered immediately after microbial infection, and one mechanism is the production of antimicrobial compounds, including small antimicrobial peptides (AMP). In recent years, it has become widely recognized that AMPs are powerful defensive weapons against bacteria and/or fungi, viruses, or parasites in multicellular organisms (). The diversity of AMPs (more than 700 online at ) and the continuous discovery of new structures make their classification particularly difficult. However, on the grounds of their structural features, these AMPs can be classified into three emerging families (for reviews, see; Bevins and Diamond 2001;; ). One family corresponds to linear peptides that can form amphipatic α-helices in a proper environment (for review, see ), the second to cyclic (open-ended or fully circular) peptides containing cysteine-residues engaged in at least one cysteine bond and adopting a β-hairpin fold (for review, see ), and the third to peptides with a preponderance of one or two amino acids (proline, arginine, glycine, or tryptophan) (for review, see ). Dec 8, 2018 - Looking for cours de biophysique optique pdf merge. Allouache programme 1 generalites sur les solutions les melanges homogenes et. The solution structure of termicin from hemocytes of the termite Pseudacanthotermes spiniger was determined by proton two-dimensional nuclear magnetic. Biophysique Des Solutions Pdf DownloadIn recent decades, a new family of cysteine rich peptides, the defensins, has been identified, and has emerged as the most widespread. Defensins are compact (3 to 5 kD) protease-resistant molecules containing three or four disulfide bridges. They have been isolated from invertebrates (), plants (), and vertebrates (). Mammalian defensins (α and β defensins) adopt a β-sheet structure including a three-stranded antiparallel β-sheet with an amphiphilic character, while the architecture of the group of invertebrate and plant defensins includes an α-helix and a β-sheet linked by two disulfide bridges. Together, the structural elements of the latter group make up the so-called CSαβ motif, for cysteine-stabilized α-helix/β-sheet motif (; ). This motif is found in antibacterial and antifungal insect defensins (;;,; ), and in the mussel defensin MGD-1 (). Compared to the antibacterial defensins with a αββ scaffold, the particularity of drosomycin (, ) and heliomicin (), the two strictly antifungal defensins from insects, is the presence of a third strand in the β-sheet, resulting in a βαββ scaffold. In addition, it has been pointed out that all antifungal defensins from insect and plants exhibit a common amphipathic character at the surface of the molecules (). Recently, a novel cysteine-rich peptide, named termicin, has been isolated from the fungus-growing termite Pseudacanthotermes spiniger, a heterometabolous insect of the order of isoptera (). Termicin is not induced by bacterial challenge as observed in all insect species but is constitutively expressed. Although termicin does not show sequence similarities with drosomycin or heliomicin, its activity spectrum is closer to that of the antifungal defensins than to that of the antibacterial defensins. ![]() Biophysique Des Solutions Pdf FileIn fact, the peptide exhibits a potent antifungal activity but only weakly affects Gram-positive bacteria. This 36-residue peptide shows no obvious similarities with other AMPs except for the consensus motif of cysteine residues forming the disulfide scaffold characteristic of the CSαβ motif. The past decades have witnessed a dramatic growth in knowledge of natural AMPs, and the goal now is to obtain as much information as possible regarding the structures of the molecules and their biologic properties. In an attempt to design strain specific AMPs, the first step is to understand the structural elements required for an antifungal activity or an antibacterial activity. In this study, we have determined the structure of termicin in aqueous solution using two-dimensional NMR spectroscopy and molecular modeling. The global fold involves an α-helix and a double-stranded β-sheet. This solution structure was compared to drosomycin and heliomicin (the two known antifungal defensins from insects), to the antibacterial Phormia defensin A, and to MGD-1, the mussel antibacterial defensin. In contrast to its biologic properties (mainly antifungal), the global fold of termicin is reminiscent of the antibacterial defensins. NMR Following the production of recombinant termicin in the yeast Saccharomyces cerevisiae (see the general procedure reported by ), termicin was purified to homogeneity by reverse-phase HPLC and dissolved in 90% H 2O:10% D 2O for NMR experiments.
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