Alejandra Viviana Quiroga

Amaranth (Amaranthus hypochondriacus) vicilin subunit structure.

The 7S-globulin fraction is a minor component of the amaranth storage proteins. The present work provides new information about this protein. The amaranth 7S-globulin or vicilin presented a sedimentation coefficient of 8.6 ± 0.6 S and was composed of main subunits of 66, 52, 38, and 16 kDa. On the basis of mass spectrometry (MS) analysis of tryptic fragments, the 52, 38, and 16 kDa subunits presented sequence homology with sesame vicilin, whereas the 66 kDa subunit showed sequence similarity with a putative vicilin. Several characteristics of the 66 kDa subunit were similar to members of the convicilin family. Results support the hypothesis that the 7S-globulin molecules are composed of subunits coming from at least two gene families with primary products of 66 and 52 kDa, respectively. According to the present information, amaranth vicilin may be classified into the vicilin group that includes pea, broad bean, and sesame vicilins, among others.

Physicochemical, functional and angiotensin converting enzyme inhibitory properties of amaranth (Amaranthus hypochondriacus) 7S globulin

BACKGROUND Amaranth 7S globulin is a minor globulin component and its impact on the properties of an amaranth protein ingredient depends on its proportion in the variety of amaranth being considered. Some physicochemical, functional and angiotesin I-converting enzyme (ACE) inhibitory properties of amaranth vicilin were studied in this work and compared with the 11S globulin. RESULTS Fluorescence spectroscopy results indicated that 7S globulin tryptophans were more exposed to the solvent and, by calorimetry, the 7S globulin denaturation temperature (T(d) ) was found lower than the 11S globulin T(d) , suggesting a more flexible structure. The 7S globulin surface hydrophobicity was higher than that of the 11S globulin, which is in agreement with the better emulsifying properties of the 7S globulin. The solubility in neutral buffer of the 7S globulin (851 ± 25 g kg(-1) ) was also higher than that of the 11S globulin (195 ± 6 g kg(-1) ). Bioinformatic analyses showed the presence of ACE inhibitory peptides encrypted in 7S tryptic sequences and peptides released after in vitro gastrointestinal digestion showed a high ACE-inhibitory capacity (IC(50) = 0.17 g L(-1) ), similar to that of 11S globulin peptides. CONCLUSION Compared with the 11S globulin, the 7S globulin presents similar ACE inhibitory activity and some functional advantages, better solubility and emulsifying activity, which suits some food requirements. The functional behavior has been related with the structural properties.

Globulin-p and 11S-Globulin from Amaranthus Hypochondriacus : are Two Isoforms of the 11S-Globulin

Amaranth is an ancient crop with a high content of good quality proteins. Globulins are some of the most abundant storage proteins of amaranth grain. They contain two fractions distinguishable according to their different solubility: the salt-soluble 7S and 11S-globulins and the globulin-p soluble in mild-alkaline, low-ionic-strength solutions. As part of the amaranth proteins characterization, in this work we investigated the structural characteristics responsible for the different physicochemical properties of these globulins. We studied certain conformational parameters of the purified aggregates (AMGp) and individual molecules (IMGp) of globulin-p and of the partially purified globulin (ppGb) and compared the AMGp polypeptide sequences with the sequence of the 11S-globulin propolypeptide from Amaranthus (gi|122726601). The results indicated that the AMGp aggregates are responsible for the different solubility of globulin-p. Subtle conformational differences as determined by fluorescence spectroscopy and urea sensitivity were found between the molecules studied: The AMGp showed some surface differences from the IMGp and the ppGb; the AMGp also had a lower affinity for the hydrophobic fluorescent probe 1,8-aniline-naphthalene-sulfonate and a higher ionic charge than the ppGb and the IMGp, characteristics that might cause their lower solubility. In addition, we have demonstrated differences between the AMGp polypeptide sequences and that reported for amaranth 11S-globulin. These differences suggest that the globulin-p and 11S-globulin are two 11S-globulin isoforms comprised of polypeptides coming from different legumin-gene subfamilies.

Identification of cross-reactive B-cell epitopes between Bos d 9.0101(Bos Taurus) and Gly m 5.0101 (Glycine max) by epitope mapping MALDI-TOF MS

Exposure to cows milk constitutes one of the most common causes of food allergy. In addition, exposure to soy proteins has become relevant in a restricted proportion of milk allergic pediatric patients treated with soy formulae as a dairy substitute, because of the cross‐allergenicity described between soy and milk proteins. We have previously identified several cross‐reactive allergens between milk and soy that may explain this intolerance. The purpose of the present work was to identify epitopes in the purified αS1‐casein and the recombinant soy allergen Gly m 5.0101 (Gly m 5) using an α‐casein‐specific monoclonal antibody (1D5 mAb) through two different approaches for epitope mapping, to understand cross‐reactivity between milk and soy. The 1D5 mAb was immobilized onto magnetic beads, incubated with the peptide mixture previously obtained by enzymatic digestion of the allergens, and the captured peptides were identified by MALDI‐TOF MS analysis. On a second approach, the peptide mixture was resolved by RP‐HPLC and immunodominant peptides were identified by dot blot with the mAb. Finally, recognized peptides were sequenced by MALDI‐TOF MS. This novel MS based approach led us to identify and characterize four peptides on α‐casein and three peptides on Gly m 5 with a common core motif. Information obtained from these cross‐reactive epitopes allows us to gain valuable insight into the molecular mechanisms of cross‐reactivity, to further develop new and more effective vaccines for food allergy.

In Vitro Modulation of Renin–Angiotensin System Enzymes by Amaranth (Amaranthus hypochondriacus) Protein-Derived Peptides: Alternative Mechanisms Different from ACE Inhibition

Among the factors affecting the development of cardiovascular diseases, hypertension is one of the most important. Research done on amaranth proteins has demonstrated their hypotensive capacity in vivo and in vitro; nevertheless, the mechanism underlying this effect remains unclear. The aim of this study was to analyze in vitro the inhibition of peptides derived from an amaranth hydrolysate (AHH) on other RAS enzymes other than ACE. The chymase and renin activities were studied. AHH was not able to inhibit chymase activity, although a dose-response effect was found on renin activity (IC50 0.6 mg/mL). To provide an approach to the renin inhibition mechanism, we analyzed AHH renin inhibition kinetics and performed a structural characterization of the peptides involved in the effect in terms of molecular size and hydrophobicity. Results suggest that amaranth peptides exhibit renin competitive inhibition behavior. Renin inhibition potency was directly related to peptide hydrophobicity. RP-HPLC separation of AHH and subsequent analysis of the peptide sequences showed 6 peptides belonging to 11S globulin (that can be grouped into 3 families) that would be responsible for renin inhibition. These results demonstrate that Amaranthus hypochondriacus seeds are an adequate source of peptides with renin inhibitory properties that could be used in functional food formulations.

Two years of surveillance of influenza a virus infection in a swine herd. Results of virological, serological and pathological studies

Swine farms provide a dynamic environment for the evolution of influenza A viruses (IAVs). The present report shows the results of a surveillance effort of IAV infection in one commercial swine farm in Argentina. Two cross-sectional serological and virological studies (n=480) were carried out in 2011 and 2012. Virus shedding was detected in nasal samples from pigs from ages 7, 21 and 42-days old. More than 90% of sows and gilts but less than 40% of 21-days old piglets had antibodies against IAV. In addition, IAV was detected in 8/17 nasal swabs and 10/15 lung samples taken from necropsied pigs. A subset of these samples was further processed for virus isolation resulting in 6 viruses of the H1N2 subtype (δ2 cluster). Pathological studies revealed an association between suppurative bronchopneumonia and necrotizing bronchiolitis with IAV positive samples. Statistical analyses showed that the degree of lesions in bronchi, bronchiole, and alveoli was higher in lungs positive to IAV. The results of this study depict the relevance of continuing long-term active surveillance of IAV in swine populations to establish IAV evolution relevant to swine and humans.