RESUMEN
Glycocin F (GccF), a ribosomally synthesized, post-translationally modified peptide secreted by Lactobacillus plantarum KW30, rapidly inhibits the growth of susceptible bacteria at nanomolar concentrations. Previous studies have highlighted structural features important for its activity and have shown the absolute requirement for the Ser18 O-linked GlcNAc on the eight-residue loop linking the two short helices of the (C-X6-C)2 structure. Here, we show that an ostensibly very small chemical modification to Ser18, the substitution of the Cα proton with a methyl group, reduces the antimicrobial activity of GccF 1000-fold (IC50 1.5 µM cf. 1.5 nM). A comparison of the GccFα-methylSer18 NMR structure (PDB 8DFZ) with that of the native protein (PDB 2KUY) showed a marked difference in the orientation and mobility of the loop, as well as a markedly different positioning of the GlcNAc, suggesting that loop conformation, dynamics, and glycan presentation play an important role in the interaction of GccF with as yet unknown but essential physiological target molecules.
Asunto(s)
Antiinfecciosos , Péptidos , Péptidos/química , Espectroscopía de Resonancia Magnética , Imagen por Resonancia Magnética , Estructura Secundaria de Proteína , Antiinfecciosos/farmacologíaRESUMEN
The emergence of multidrug-resistant pathogens has motivated natural product research to inform the development of new antimicrobial agents. Glycocin F (GccF) is a diglycosylated 43-amino-acid bacteriocin secreted by Lactobacillus plantarum KW30. It displays a moderate phylogenetic target range that includes vancomycin-resistant strains of Enterococcus species and appears to have a novel bacteriostatic mechanism, rapidly inhibiting the growth of the most susceptible bacterial strains at picomolar concentrations. Experimental verification of the predicted role(s) of gcc cluster genes in GccF biosynthesis has been hampered by the inability to produce soluble recombinant Gcc proteins. Here, we report the development of pRV610gcc, an easily modifiable 11.2-kbp plasmid that enables the production of GccF in L. plantarum NC8. gcc gene expression relies on native promoters in the cloned cluster, and NC8(pRV610gcc) produces mature GccF at levels similar to KW30. Key findings are that the glycosyltransferase glycosylates both serine and cysteine at either position in the sequence but glycosylation of the loop serine is both sequence and spatially specific, that glycosylation of the peptide scaffold is not required for export and subsequent disulfide bond formation, that neither of the putative thioredoxin proteins is essential for peptide maturation, and that removal of the entire putative response regulator GccE decreases GccF production less than removal of the LytTR domain alone. Using this system, we have verified the functions of most of the gcc genes and have advanced our understanding of the roles of GccF structure in its maturation and antibacterial activity.IMPORTANCE The entire 7-gene cluster for the diglycosylated bacteriocin glycocin F (GccF), including the natural promoters responsible for gcc gene expression, has been ligated into the Escherichia coli-lactic acid bacteria (LAB) shuttle vector pRV610 to produce the easily modifiable 11.2-kbp plasmid pRV610gcc for the efficient production of glycocin F analogues. In contrast to the refactoring approach, chemical synthesis, or chemoenzymatic synthesis, all of which have been successfully used to probe glycocin structure and function, this plasmid can also be used to probe in vivo the evolutionary constraints on glycocin scaffolds and their processing by the maturation pathway machinery, thus increasing understanding of the enzymes involved, the order in which they act, and how they are regulated.
Asunto(s)
Antibacterianos/biosíntesis , Bacteriocinas/biosíntesis , Lactobacillus plantarum/metabolismo , Familia de Multigenes , Bacteriocinas/química , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Vectores Genéticos/genética , Vectores Genéticos/metabolismo , Glicosilación , Lactobacillus plantarum/genética , Filogenia , Plásmidos/genética , Plásmidos/metabolismoRESUMEN
Yeast impact homolog 1 (Yih1), or IMPACT in mammals, is part of a conserved regulatory module controlling the activity of General Control Nonderepressible 2 (Gcn2), a protein kinase that regulates protein synthesis. Yih1/IMPACT is implicated not only in many essential cellular processes, such as neuronal development, immune system regulation and the cell cycle, but also in cancer. Gcn2 must bind to Gcn1 in order to impair the initiation of protein translation. Yih1 hinders this key Gcn1-Gcn2 interaction by binding to Gcn1, thus preventing Gcn2-mediated inhibition of protein synthesis. Here, we solved the structures of the two domains of Saccharomyces cerevisiae Yih1 separately using Nuclear Magnetic Resonance and determined the relative positions of the two domains using a range of biophysical methods. Our findings support a compact structural model of Yih1 in which the residues required for Gcn1 binding are buried in the interface. This model strongly implies that Yih1 undergoes a large conformational rearrangement from a latent closed state to a primed open state to bind Gcn1. Our study provides structural insight into the interactions of Yih1 with partner molecules.
Asunto(s)
Proteínas de Microfilamentos/química , Proteínas Serina-Treonina Quinasas/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/química , Secuencia de Aminoácidos , Animales , Sitios de Unión , Clonación Molecular , Medios de Contraste/química , Escherichia coli/genética , Escherichia coli/metabolismo , Gadolinio DTPA/química , Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Ratones , Proteínas de Microfilamentos/genética , Proteínas de Microfilamentos/metabolismo , Modelos Moleculares , Mutación , Resonancia Magnética Nuclear Biomolecular , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , Dominios y Motivos de Interacción de Proteínas , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , TermodinámicaRESUMEN
Here, we report on the biochemical characterization of a new glycosylated bacteriocin (glycocin), ASM1, produced by Lactobacillus plantarum A-1 and analysis of the A-1 bacteriocinogenic genes. ASM1 is 43 amino acids in length with Ser18-O- and Cys43-S-linked N-acetylglucosamine moieties that are essential for its inhibitory activity. Its only close homologue, glycocin F (GccF), has five amino acid substitutions all residing in the flexible C-terminal 'tail' and a lower IC50 (0.9 nm) compared to that of ASM1 (1.5 nm). Asm/gcc genes share the same organization (asmHâ âasmABCDEâF), and the asm genes reside on an 11 905-bp plasmid dedicated to ASM1 production. The A-1 genome also harbors a gene encoding a 'rare' bactofencin-type bacteriocin. As more examples of prokaryote S-GlcNAcylation are discovered, the functions of this modification may be understood.
Asunto(s)
Bacteriocinas/química , Bacteriocinas/metabolismo , Lactobacillus plantarum/química , Lactobacillus plantarum/genética , Plásmidos/genética , Secuencia de Aminoácidos , Bacteriocinas/genética , Secuencia de Bases , Genes Bacterianos/genética , Glicosilación , Novobiocina , Filogenia , Análisis de Secuencia de ADNRESUMEN
Here we demonstrate G-quadruplex formation by oligodeoxynucleotides containing α-2'-deoxyguanosine (α-dG) as a sole source of guanosines in G4T4, G4T4G4 and T(G3Tn)3G3T sequences with various numbers of natural ß-T in the loops (n = 1-4). Based on circular dichroism spectra we observed that all α-dG-containing DNAs formed G-quadruplexes with uniform arrangement of α-dG-tetrads, which implies formation of G-quadruplexes of parallel topology. In several cases, native DNA structures that usually adopt an antiparallel topology were converted to more thermally stable G-quadruplexes of parallel topology. Using 2D ROESY NMR spectra a new 'sequential walk' was established for α-dGs in a tetramolecular, parallel complex formed by the α-G4ß-T4 sequence. Analysis of ROEs in α-dGs indicates that guanines in [α-G4ß-T4]4 adopt anti-glycosidic conformations. These results demonstrate that α-dG can be used for an antiparallel-to-parallel switch of G-quadruplex DNAs producing complexes with higher thermal stability and uniform stacking of α-dG-tetrads.
Asunto(s)
ADN/química , Desoxiguanosina/química , G-Cuádruplex , Resonancia Magnética Nuclear BiomolecularRESUMEN
Antibacterial compounds known as bacteriocins are microbial inventions designed to reduce the competition for limited resources by inhibiting the growth of closely related bacteria. Glycocin F (GccF) is an unusually di-glycosylated bacteriocin produced in a lactic acid bacterium, Lactobacillus plantarum KW30 that has been shown to be resistant to extreme conditions. It is bacteriostatic rather than bactericidal, and all its post-translational modifications (a pair of nested disulfide bonds, and O-linked and S-linked N-acetylglucosamines) are required for full activity. Here, we examine a cluster of genes predicted to be responsible for GccF expression and maturation. The expression of eight genes, previously reported to make up the gcc operon, was profiled for their expression during cell culture. We found that all but one of the genes of the gcc cluster followed a pattern of expression that correlated with the stage of growth observed for the producer organism along with the increase in GccF secretion. We also found that most of the gcc genes are transcribed as a single unit. These data provide evidence that the gcc cluster genes gccABCDEF constitute a true operon for regulated GccF production, and explain the observed increase in GccF concentration that accompanies an increase in cell numbers.
Asunto(s)
Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Bacteriocinas/biosíntesis , Expresión Génica , Lactobacillus plantarum/genética , Lactobacillus plantarum/metabolismo , Antibacterianos/biosíntesis , Vías Biosintéticas/genética , Perfilación de la Expresión Génica , Regulación Bacteriana de la Expresión Génica , Lactobacillus plantarum/crecimiento & desarrollo , Familia de Multigenes , Operón , Transcripción GenéticaRESUMEN
Glycocin F (GccF) is a unique diglycosylated bacteriocin peptide that possesses potent and reversible bacteriostatic activity against a range of Gram-positive bacteria. GccF is a rare example of a 'glycoactive' bacteriocin, with both the O-linked N-acetylglucosamine (GlcNAc) and the unusual S-linked GlcNAc moiety important for antibacterial activity. In this report, glycocin F was successfully prepared using a native chemical ligation strategy and folded into its native structure. The chemically synthesised glycocin appeared to be slightly more active than the recombinant material produced from Lactobacillus plantarum. A second-generation synthetic strategy was used to prepare 2 site selective 'glyco-mutants' containing either two S-linked or two O-linked GlcNAc moieties; these mutants were used to probe the contribution of each type of glycosidic linkage to bacteriostatic activity. Replacing the S-linked GlcNAc at residue 43 with an O-linked GlcNAc decreased the antibacterial activity, while replacing O-linked GlcNAc at position 18 with an S-linked GlcNAc increased the bioactivity suggesting that the S-glycosidic linkage may offer a biologically-inspired route towards more active bacteriocins.
RESUMEN
Glycocin F, a bacteriocin produced by Lactobacillus plantarum KW30, is glycosylated with two N-acetyl-d-glucosamine sugars, and has been shown to exhibit a rapid and reversible bacteriostasis on susceptible cells. The roles of certain structural features of glycocin F have not been studied to date. We report here the synthesis of various glycocin F analogues through solid-phase peptide synthesis (SPPS) and native chemical ligation (NCL), allowing us to probe the roles of different structural features of this peptide. Our results indicate that the bacteriostatic activity of glycocin F is controlled by the glycosylated interhelical loop, while the glycosylated flexible tail appears to be involved in localizing the peptide to its cellular target.
Asunto(s)
Bacteriocinas/síntesis química , Bacteriocinas/farmacología , Sondas Moleculares/química , Péptidos/síntesis química , Péptidos/farmacología , Bacteriocinas/química , Péptidos/química , Relación Estructura-ActividadRESUMEN
First reported in 2011, glycocins (glycosylated bacteriocins) are bacterial toxins that constitute a subset of ribosomally synthesised and post-translationally modified peptide (RiPP) natural products. Three NMR structures (glycocin F, ASM1 and sublancin 168), two with helix-loop-helix Cs α/α folds, are deposited in the PDB. Each structure contains a monosaccharide ß-S-linked to a cysteine side chain. Three more glycocins (thurandacin, and enterocins F4-9 and 96) have been biochemically characterised, and others predicted on the basis of bioinformatic analyses. Only glycocin F, ASM1 and enterocin F4-9 are unequivocally glycoactive. This review probes the structure-function relationships of four types of nested disulfide-bonded glycocins.
Asunto(s)
Bacteriocinas/metabolismo , Bacteriocinas/antagonistas & inhibidores , Bacteriocinas/química , GlicosilaciónRESUMEN
The first total synthesis of glycocinâ F, a uniquely diglycosylated antimicrobial peptide bearing a rare S-linked N-acetylglucosamine (GlcNAc) moiety in addition to an O-linked GlcNAc, has been accomplished using a native chemical ligation strategy. The synthetic and naturally occurring peptides were compared by HPLC, mass spectrometry, NMR and CD spectroscopy, and their stability towards chymotrypsin digestion and antimicrobial activity were measured. This is the first comprehensive structural and functional comparison of a naturally occurring glycocin with an active synthetic analogue.
Asunto(s)
Antiinfecciosos/síntesis química , Bacteriocinas/síntesis química , Glicopéptidos/síntesis química , Péptidos/síntesis química , Antiinfecciosos/química , Bacteriocinas/química , Cromatografía Líquida de Alta Presión , Glicopéptidos/química , Glicosilación , Péptidos/químicaRESUMEN
ß-Lactoglobulin (ßlg) is the most abundant whey protein in the milks of ruminant animals. While bovine ßlg has been subjected to a vast array of studies, little is known about the caprine ortholog. We present an ultra-high resolution crystal structure of caprine ßlg complemented by analytical ultracentrifugation and small-angle X-ray scattering data. In both solution and crystalline states caprine ßlg is dimeric (K(D)<5 µM); however, our data suggest a flexible quaternary arrangement of subunits within the dimer. These structural findings will provide insight into relationships among structural, processing, nutritional and immunological characteristics that distinguish cow's and goat's milk.
Asunto(s)
Cabras , Lactoglobulinas/química , Proteínas Recombinantes/química , Secuencia de Aminoácidos , Animales , Bovinos , Fenómenos Químicos , Cristalografía por Rayos X , Lactoglobulinas/genética , Lactoglobulinas/aislamiento & purificación , Modelos Moleculares , Datos de Secuencia Molecular , Estructura Cuaternaria de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificaciónRESUMEN
New helicase assays that recognise therapeutically important G4-DNA structures will lead to the discovery of novel molecular entities that bind not only to G4-tetrads, but also to grooves and loops of G4-DNA. Such assays can also provide inhibitors of G4-specific helicases that will shed light on the emerging involvement of helicases in cancer and other diseases linked to defective DNA repair pathways.
Asunto(s)
ADN Helicasas/química , Inhibidores Enzimáticos/síntesis química , G-Cuádruplex , Antineoplásicos/síntesis química , Antineoplásicos/farmacología , ADN Helicasas/antagonistas & inhibidores , Reparación del ADN/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Ensayos Analíticos de Alto Rendimiento , Humanos , Telomerasa/antagonistas & inhibidoresRESUMEN
Bovine ß-lactoglobulin (ß-Lg) self-assembles into long amyloid-like fibrils when heated at 80 °C, pH 2, and low ionic strength (<0.015 mM). Heating ß-Lg under fibril-forming conditions shows a lag phase before fibrils start forming. We have investigated the structural characteristics of ß-Lg during the lag phase and the composition of ß-Lg fibrils after their separation using ultracentrifugation. During the lag phase, the circular dichroism spectra of heated ß-Lg showed rapid unfolding, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of samples showed increasing hydrolysis of ß-Lg. The SDS-PAGE profiles of fibrils separated by ultra centrifugation showed that after six hours, the fibrils consisted of a few preferentially accumulated peptides. Two-dimensional SDS-PAGE under reducing and nonreducing conditions showed the presence of disulfide-bonded fragments in the fibrils. The sequences in these peptide bands were characterized by in-gel digestion electrospray ionization (ESI)-MS/MS. The composition of solubilized fibrils was also characterized by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) MS/MS. Both MS analyses showed that peptides in fibrils were primarily from the N-terminal region, although there was some evidence of peptides from the C-terminal part of the molecule present in the higher molecular weight gel bands. We suggest that although the N-terminal region of ß-Lg is almost certainly involved in the formation of the fibrils, other peptide fragments linked through disulfide bonds may also be present in the fibrils during self-assembly.
Asunto(s)
Disulfuros/química , Lactoglobulinas/química , Secuencias de Aminoácidos , Animales , Bovinos , Calor , Concentración de Iones de Hidrógeno , Concentración Osmolar , Conformación Proteica , Pliegue de Proteína , Desplegamiento ProteicoRESUMEN
This review presents recommended nomenclature for the biosynthesis of ribosomally synthesized and post-translationally modified peptides (RiPPs), a rapidly growing class of natural products. The current knowledge regarding the biosynthesis of the >20 distinct compound classes is also reviewed, and commonalities are discussed.
Asunto(s)
Productos Biológicos , Péptidos , Ribosomas/metabolismo , Secuencia de Aminoácidos , Productos Biológicos/síntesis química , Productos Biológicos/química , Productos Biológicos/clasificación , Productos Biológicos/farmacología , Humanos , Datos de Secuencia Molecular , Estructura Molecular , Péptidos/síntesis química , Péptidos/química , Péptidos/clasificación , Péptidos/farmacología , Procesamiento Proteico-Postraduccional , Ribosomas/genéticaRESUMEN
The oligomerization of ß-lactoglobulin (ßLg) has been studied extensively, but with somewhat contradictory results. Using analytical ultracentrifugation in both sedimentation equilibrium and sedimentation velocity modes, we studied the oligomerization of ßLg variants A and B over a pH range of 2.5-7.5 in 100 mM NaCl at 25°C. For the first time, to our knowledge, we were able to estimate rate constants (k(off)) for ßLg dimer dissociation. At pH 2.5 k(off) is low (0.008 and 0.009 s(-1)), but at higher pH (6.5 and 7.5) k(off) is considerably greater (>0.1 s(-1)). We analyzed the sedimentation velocity data using the van Holde-Weischet method, and the results were consistent with a monomer-dimer reversible self-association at pH 2.5, 3.5, 6.5, and 7.5. Dimer dissociation constants K(D)(2-1) fell close to or within the protein concentration range of â¼5 to â¼45 µM, and at â¼45 µM the dimer predominated. No species larger than the dimer could be detected. The K(D)(2-1) increased as |pH-pI| increased, indicating that the hydrophobic effect is the major factor stabilizing the dimer, and suggesting that, especially at low pH, electrostatic repulsion destabilizes the dimer. Therefore, through Poisson-Boltzmann calculations, we determined the electrostatic dimerization energy and the ionic charge distribution as a function of ionic strength at pH above (pH 7.5) and below (pH 2.5) the isoelectric point (pIâ¼5.3). We propose a mechanism for dimer stabilization whereby the added ionic species screen and neutralize charges in the vicinity of the dimer interface. The electrostatic forces of the ion cloud surrounding ßLg play a key role in the thermodynamics and kinetics of dimer association/dissociation.
Asunto(s)
Lactoglobulinas/química , Lactoglobulinas/metabolismo , Multimerización de Proteína , Animales , Bovinos , Concentración de Iones de Hidrógeno , Cinética , Modelos Moleculares , Peso Molecular , Unión Proteica , Estabilidad Proteica , Electricidad Estática , Termodinámica , UltracentrifugaciónRESUMEN
Campylobacter and Helicobacter species express a 6-amino-6-deoxyfutalosine N-ribosylhydrolase (HpMTAN) proposed to function in menaquinone synthesis. BuT-DADMe-ImmA is a 36 pM transition state analogue of HpMTAN, and the crystal structure of the enzyme-inhibitor complex reveals the mechanism of inhibition. BuT-DADMe-ImmA has a MIC(90) value of <8 ng/mL for Helicobacter pylori growth but does not cause growth arrest in other common clinical pathogens, thus demonstrating potential as an H. pylori-specific antibiotic.
Asunto(s)
Adenina/análogos & derivados , Antibacterianos/química , Antibacterianos/farmacología , Helicobacter pylori/efectos de los fármacos , Helicobacter pylori/enzimología , N-Glicosil Hidrolasas/antagonistas & inhibidores , Pirrolidinas/química , Pirrolidinas/farmacología , Adenina/química , Adenina/farmacología , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Infecciones por Helicobacter/tratamiento farmacológico , Humanos , Modelos Moleculares , N-Glicosil Hidrolasas/metabolismoRESUMEN
The distribution and effect of applied strain on the collagen fibrils that make up leather may have an important bearing on the ultimate strength and other physical properties of the material. While sections of ovine and bovine leather were being subjected to tensile strain up to rupture, synchrotron-based small-angle X-ray scattering (SAXS) spectra were recorded edge-on to the leather at points from the corium to the grain. Measurements of both fibril orientation and collagen d spacing showed that, initially, the fibers reorient under strain, becoming more aligned. As the strain increases (5-10% strain), further fibril reorientation diminishes until, at 37% strain, the d spacing increases by up to 0.56%, indicating that significant tensile forces are being transmitted to individual fibrils. These changes, however, are not uniform through the cross-section of leather and differ between leathers of different strengths. The stresses are taken up more evenly through the leather cross-section in stronger leathers in comparison to weaker leathers, where stresses tended to be concentrated during strain. These observations contribute to our understanding of the internal strains and structural changes that take place in leather under stress.
Asunto(s)
Colágeno/química , Piel/química , Animales , Bovinos , Elasticidad , Dispersión del Ángulo Pequeño , Ovinos , Resistencia a la Tracción , Difracción de Rayos XRESUMEN
Bacteriocins are bacterial peptides with specific activity against competing species. They hold great potential as natural preservatives and for their probiotic effects. We show here nuclear magnetic resonance-based evidence that glycocin F, a 43-amino acid bacteriocin from Lactobacillus plantarum, contains two ß-linked N-acetylglucosamine moieties, attached via side chain linkages to a serine via oxygen, and to a cysteine via sulfur. The latter linkage is novel and has helped to establish a new type of post-translational modification, the S-linked sugar. The peptide conformation consists primarily of two α-helices held together by a pair of nested disulfide bonds. The serine-linked sugar is positioned on a short loop sequentially connecting the two helices, while the cysteine-linked sugar presents at the end of a long disordered C-terminal tail. The differing chemical and conformational stabilities of the two N-actetylglucosamine moieties provide clues about the possible mode of action of this bacteriostatic peptide.
Asunto(s)
Bacteriocinas/química , Espectroscopía de Resonancia Magnética/métodos , Conformación Proteica , Estructura Secundaria de Proteína , Acetilglucosamina/química , Bacteriocinas/metabolismo , Cisteína/química , Disulfuros/química , Glicosilación , Cinética , Lactobacillus plantarum/metabolismo , Modelos Moleculares , Oxígeno/química , Procesamiento Proteico-Postraduccional , Serina/química , Azufre/químicaRESUMEN
O-Glycosylation is a ubiquitous eukaryotic post-translational modification, whereas early reports of S-linked glycopeptides have never been verified. Prokaryotes also glycosylate proteins, but there are no confirmed examples of sidechain glycosylation in ribosomal antimicrobial polypeptides collectively known as bacteriocins. Here we show that glycocin F, a bacteriocin secreted by Lactobacillus plantarum KW30, is modified by an N-acetylglucosamine ß-O-linked to Ser18, and an N-acetylhexosamine S-linked to C-terminal Cys43. The O-linked N-acetylglucosamine is essential for bacteriostatic activity, and the C-terminus is required for full potency (IC(50) 2 nM). Genomic context analysis identified diverse putative glycopeptide bacteriocins in Firmicutes. One of these, the reputed lantibiotic sublancin, was shown to contain a hexose S-linked to Cys22.
Asunto(s)
Bacteriocinas/química , Bacteriocinas/metabolismo , Cisteína/metabolismo , Glicopéptidos/metabolismo , Procesamiento Proteico-Postraduccional , Acetilglucosamina/metabolismo , Bacillus subtilis/metabolismo , Bacteriocinas/genética , Bacteriocinas/aislamiento & purificación , Secuencia de Bases , Dicroismo Circular , Glicosilación , Bacterias Grampositivas/genética , Bacterias Grampositivas/metabolismo , Hexosaminas/metabolismo , Concentración 50 Inhibidora , Lactobacillales/efectos de los fármacos , Lactobacillus plantarum/metabolismo , Espectrometría de Masas , Datos de Secuencia Molecular , Fragmentos de Péptidos/química , Fragmentos de Péptidos/metabolismo , Fragmentos de Péptidos/farmacología , Péptidos/química , Péptidos/metabolismo , Señales de Clasificación de Proteína , SerinaRESUMEN
SAXS has been applied to structural determination in leather. The SAXS beamline at the Australian Synchrotron provides 6 orders of magnitude dynamic range, enabling a rich source of structural information from scattering patterns of leather sections. SAXS patterns were recorded for q from 0.004 to 0.223 A(-1). Collagen d spacing varied across ovine leather sections from 63.8 nm in parts of the corium up to 64.6 nm in parts of the grain. The intensity of the collagen peak at q = 0.06 A(-1) varied by 1 order of magnitude across ovine leather sections with the high-intensity region in the corium and the low intensity in the grain. The degree of fiber orientation and the dispersion of the orientation has been quantified in leather. It is shown how the technique provides a wealth of useful information that may be used to characterize and compare leathers, skin, and connective tissue.