Isolation and characterization of beta-gliadin fractions

Self-organization of gliadin in aqueous media under physiological digestive pHs

Here we showed that gliadin, a complex protein system related to celiac disease and other human diseases, is spontaneously self-organized in a very dilute solution at pH 3.0 and 7.0 in water under low ionic strength (10mM NaCl). The spontaneous self-organization at pH 3.0 increases the apparent solubility due to the formation of finite sized aggregates, such as those formed in the micellization of amphiphilic molecules. Switching the pH from 3.0 to 7.0 lead to a phase separation, however part of the nano-particles are stable remaining disperse in water after centrifugation. Also, beside the pH change led to changes in protein composition and concentration, we determined that the secondary structure of both system is the same. Moreover, Tyrs are slightly more buried and Trps are slightly more exposed to water at pH 7.0 than those at pH 3.0. Electron microscopy techniques showed that both gliadin systems are composed of nanostructures and in the case of pH 7.0 amorphous microaggregates were found, too. Only nanostructures at pH 3.0 showed a micromolar binding affinity to Nile red probe, suggesting the presence of accessible hydrophobic patches which are not more accessible at pH 7.0. All our results suggest that gliadin is able to self-organized at pH 3.0 forming protein micelles type nanostructures (ζ=+13, 42 ± 1.55 mV), meanwhile at 7.0 the decrease of superficial charge to ζ of +4, 78 ± 0.48 mV led to the formation of stable colloidal nanoparticles, unable to interact with Nile red probe. Our findings may open new perspectives for the understanding of gliadin ability to avoid proteolysis, to reach and cross the intestinal lumen and to trigger different immunological disorders.

Analgesic activity of a polysaccharide in experimental osteoarthritis in rats

Viscosupplementation efficacy has been related to the high molecular weight of hyaluronic acid-like compounds, as well as to gel formulation. We evaluated the effect of a galactomannan polysaccharide derived from Guar gum (GG) in joint pain in an osteoarthritis (OA) model. Wistar rats (six animals/group) were subjected to anterior cruciate ligament transection (ACLT-OA group). The OA group was compared to a false-operated group (sham). Joint pain was recorded daily, using the articular incapacitation test, until 7 days after ACLT. Solutions or gel preparations of GG (100 microg) or Hylan G-F 20 (100 microg), used as a comparator, were given intraarticularly (i.a.) at day 4 after ACLT. Controls received saline i.a. The OA group had significantly increased joint pain as compared to sham (P<0.001). GG, either as a gel or solution, significantly inhibited joint pain similar to the inhibition achieved with Hylan G-F20. This is the first demonstration that a galactomannan derived from GG reduces joint pain in experimental OA. This analgesia is independent of the colloidal state. We propose that the analgesic benefit of viscosupplementation may be due to an intrinsic carbohydrate-mediated mechanism rather than to the rheologic properties of the material.

Correlation between gliadin bands

Starch gel electrophoresis of gliadins was carried out for 37 bread wheat cultivars chosen for their distant relationships. Simple correlations were calculated between each of the 41 bands (variates) observed with these wheats. It was found that a band is usually negatively correlated with the two neighbouring mobility bands. The number of bands positively or negatively correlated with a given band varies from 2 to 8. Taking the bands significantly positively correlated with each-other 32 groups were constituted. It appears likely that these correlations result from the fact that the genes determining the bands of a given group are situated on one chromosome. Study of the distribution of 15 gliadin bands from 312 F2 grains indicated that 2/3 of the correlations calculated for this progeny were due to linkages.