Sandbox Reserved 959
From Proteopedia
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| - | == Defensins- | + | == Defensins-Alpha-1 playing a role against trypanosoma cruzy == |
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== Introduction == | == Introduction == | ||
| - | Defensins (DEF) are a family of protein which are involved in host defenses in the epithelia of mucosal surfaces such as those of the intestin, respiratory tract, urinary tract, and vagina. There are antimicrobial and cytotoxic. All the protein of the family are distinguished by a cystein motif and are encoded on the chromozome 8 | + | Defensins (DEF) are a family of protein which are involved in host defenses in the epithelia of mucosal surfaces such as those of the intestin, respiratory tract, urinary tract, and vagina. There are antimicrobial and cytotoxic. All the protein of the family are distinguished by a cystein motif and are encoded on the chromozome 8 <ref>http://www.ncbi.nlm.nih.gov/gene/1667</ref>. There are many defensin but in this article we will focus on the defensin alpha 1. The defensin alpha 1 is a polypeptide which are found in the microbicidal granules of neutrophils. They are syntetisize in the Paneth cell, which plays a role in the defense process. <ref>https://books.google.fr/books ''Histologie et biologie cellulaire: Une introduction à l'anatomie pathologique'' Abraham L. Kierszenbaum 2002</ref>It plays a role in phagocite-mediated host defense.<br /> |
| - | In this article, we | + | In this article, we will focus on the action of the alpha defensin 1 against the ' ' trypanosoma cruzy ' '. |
| - | <StructureSection load='2pm4' size='450' side='right'caption='Crystal Structure of Defensin | + | <StructureSection load='2pm4' size='450' side='right'caption='Crystal Structure of Defensin, (PDB code [[2pm4]]) '> |
=== Biological role === | === Biological role === | ||
| - | DEF are known to play a role in the in the initiation of innate immune responses to some microbial pathogens. For example | + | DEF are known to play a role in the in the initiation of innate immune responses to some microbial pathogens. For example the alpha defensin 1 have a role against the bacteria "Trypanosoma cruzi" <ref>http://iai.asm.org/content/81/11/4139.full/ref</ref>."Trypanosoma cruzy" or "Cruzy" debilitats Chagas disease, which affects millions of people and products significant morbidity and mortality. The defensine alpha 1 are secreted by the HCT116 cells (which are Paneth cells), when they are infect by "Cruzy". They reduces the infection making damage of the flagella structure. This damage inhibit parasite motility and reduce cellular infection. This reaction is introduce in the following drawing. |
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| + | The alpha defensin peptides are secreted inactive. The α-defensins are cationic antimicrobial peptides that are synthesized in vivo as inactive precursors. Activation requires proteolytic excision of their anionic N-terminal inhibitory pro peptide. The pro peptide also specifically interacts with and inhibits the antimicrobial activity of the alpha-defensin intermolecularly.<ref>www.ncbi.nlm.nih.gov/pmc/articles/PMC2754386/ )</ref> | ||
| + | The active mature α-defensin peptides consist of 29–35 amino acid residues with a molecular mass of 3–5 kDa. | ||
| + | The primary structure shows highly conserved residues, which are indispensable for the structural stability of the peptides. Among them are six invariant cysteine residues, necessary for the typical α-defensin intramolecular disulphide-bond connectivity (Cys1–Cys6, Cys2–Cys4 and Cys3–Cys5). We can observe this bridge on the following figure. There are two charged amino acid residues, Arg5, and Glu13, forming a conserved salt bridge, and Gly17, which constitutes a signature structural motif which is essential for correct folding. | ||
| + | The tertiary structure is a triple-stranded β-sheet with a β-hairpin that contains cationic amino acid residues. | ||
<ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2049026/</ref>." | <ref>http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2049026/</ref>." | ||
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| - | [[Image: disulfure.jpg|350px|left|thumb| Defensin- | + | [[Image: disulfure.jpg|350px|left|thumb| Defensin-Alpha-1 cysteine connectivities.<ref>Stephen H Wile, William C Wimley and Michael E Selsted. Structure, function, and membrane integration of defensins. Current Opinion in Structural Biology 1995. University of California, Irvine, USA</ref>."]] |
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Introduction
Defensins (DEF) are a family of protein which are involved in host defenses in the epithelia of mucosal surfaces such as those of the intestin, respiratory tract, urinary tract, and vagina. There are antimicrobial and cytotoxic. All the protein of the family are distinguished by a cystein motif and are encoded on the chromozome 8 [1]. There are many defensin but in this article we will focus on the defensin alpha 1. The defensin alpha 1 is a polypeptide which are found in the microbicidal granules of neutrophils. They are syntetisize in the Paneth cell, which plays a role in the defense process. [2]It plays a role in phagocite-mediated host defense.
In this article, we will focus on the action of the alpha defensin 1 against the ' ' trypanosoma cruzy ' '.
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