Marcello Duranti

Legume seeds: protein content and nutritional value

Abstract Proteins are major components of legume seeds. Their nutritional and functional properties dramatically affect the overall quality of the seed and its technological performance. In this review legume seed proteins are considered, taking into account both their molecular and nutritional properties. Other compounds of non-protein origin affect the utilization of grain legumes for food and feed. They have also been reviewed both for their involvement in the seed life cycle and for human nutrition. The perspectives for improvement of legume traits, starting from the molecules considered and also including the biotechnological approaches, are also discussed.

The seed globulins of Lupinus albus

Abstract The seed globulins of Lupinus albus were extracted and 12 ditterent proteins were separated: four of them correspond to vicilins and two to legumin

Subunit composition of the seed globulins of Lupinus albus

Abstract The seed globulins separated from Lupinus albus are all oligomeric proteins. Vicilins, i.e. globulins 4,5,6 and 7, and to a minor extent legumins,

Hypoglycemic effect of lupin seed γ-conglutin in experimental animals and healthy human subjects

A lupin seed γ-conglutin-enriched preparation was tested in a glucose overload trial with both murine models and adult healthy volunteers. The results with rats showed a dose-dependent significant decrease of blood glucose concentration, which confirmed previous findings obtained with the purified protein. Moreover, three test-product doses equivalent to 630, 315, and 157.5 mg γ-conglutin, orally administered 30 min before the carbohydrate supply, showed a relevant hypoglycemic effect in human trials. Insulin concentrations were not significantly affected. The general hematic parameters did not change at all. This is the first report on the glucose-lowering effect of lupin γ-conglutin in human subjects.

Identification and characterization of a Bowman–Birk inhibitor active towards trypsin but not chymotrypsin in Lupinus albus seeds

The paper describes the purification, structural characterization and inhibitory properties of a trypsin inhibitor from Lupinus albus L., a leguminous plant believed to be devoid of any protease inhibitor. The protein has been isolated by a newly set-up procedure and characterized by direct amino acid sequencing, MALDI-TOF mass spectroscopy and circular dichroism. Inhibitory properties toward bovine trypsin and chymotrypsin, as well as its thermal and pH stabilities, have been also assessed. The inhibitor is 63 amino acid long (Mr 6858; pI 8.22) and it is capable to inhibit two trypsin molecules simultaneously, with a Kd of 4.2+/-0.4 nM, but not chymotrypsin. BLAST search against UniProtKB/TrEMBL database indicates that the inhibitor belongs to the Bowman-Birk inhibitor (BBI) family. The interest in these serine-protease inhibitors arises from the ability to prevent or suppress carcinogen-induced transformation, as shown in various in vitro and in vivo model systems.

The future of lupin as a protein crop in Europe

Europe has become heavily dependent on soya bean imports, entailing trade agreements and quality standards that do not satisfy the European citizen’s expectations. White, yellow, and narrow-leafed lupins are native European legumes that can become true alternatives to soya bean, given their elevated and high-quality protein content, potential health benefits, suitability for sustainable production, and acceptability to consumers. Nevertheless, lupin cultivation in Europe remains largely insufficient to guarantee a steady supply to the food industry, which in turn must innovate to produce attractive lupin-based protein-rich foods. Here, we address different aspects of the food supply chain that should be considered for lupin exploitation as a high-value protein source. Advanced breeding techniques are needed to provide new lupin varieties for socio-economically and environmentally sustainable cultivation. Novel processes should be optimized to obtain high-quality, safe lupin protein ingredients, and marketable foods need to be developed and offered to consumers. With such an integrated strategy, lupins can be established as an alternative protein crop, capable of promoting socio-economic growth and environmental benefits in Europe.

Identification of the basic subunit of Ara h 3 as the major allergen in a group of children allergic to peanuts

BACKGROUND Several proteins have been identified as peanut allergens; among them, Ara h 1 (7S globulin) and Ara h 2 (2S globulin) are usually considered the major allergens. OBJECTIVE To identify the major allergens in a group of children selected for their specific pattern of immunoreactivity. METHODS We identified the dominant allergen by using (1) amino acid sequencing of the bands that show the strongest IgE immunoreactivity in 1-dimensional electrophoresis and immunoblotting and (2) specific animal IgGs raised against the dominant immunoreactive band to pinpoint the allergen(s) in peanut proteins separated by 2-dimensional electrophoresis and immunoblotting. To confirm these data, we further examined the peanut proteome using serum samples from the children with the unusual immunoreactivity. RESULTS We found a group of children with marked peanut allergy who are specifically sensitized to the basic subunit of Ara h 3 (11S globulin family). CONCLUSION That the dominant immunoreactivity in these patients is in a basic subunit of Ara h 3 was unexpected, because previous studies had indicated that Ara h 3 was only a minor peanut allergen and that the identified allergenic epitopes occurred mainly in the acidic Ara h 3 subunit.

Inhibitory properties and solution structure of a potent Bowman-Birk protease inhibitor from lentil (Lens culinaris, L) seeds.

Bowman–Birk serine protease inhibitors are a family of small plant proteins, whose physiological role has not been ascertained as yet, while chemopreventive anticarcinogenic properties have repeatedly been claimed. In this work we present data on the isolation of a lentil (Lens culinaris, L., var. Macrosperma) seed trypsin inhibitor (LCTI) and its functional and structural characterization. LCTI is a 7448 Da double‐headed trypsin/chymotrypsin inhibitor with dissociation constants equal to 0.54 nm and 7.25 nm for the two proteases, respectively. The inhibitor is, however, hydrolysed by trypsin in a few minutes timescale, leading to a dramatic loss of its affinity for the enzyme. This is due to a substantial difference in the kon and k*on values (1.1 µm−1·s−1 vs. 0.002 µm−1·s−1), respectively, for the intact and modified inhibitor. A similar behaviour was not observed with chymotrypsin. The twenty best NMR structures concurrently showed a canonical Bowman–Birk inhibitor (BBI) conformation with two antipodal β‐hairpins containing the inhibitory domains. The tertiary structure is stabilized by ion pairs and hydrogen bonds involving the side chain and backbone of Asp10‐Asp26‐Arg28 and Asp36‐Asp52 residues. At physiological pH, the final structure results in an asymmetric distribution of opposite charges with a negative electrostatic potential, centred on the C‐terminus, and a highly positive potential, surrounding the antitryptic domain. The segment 53–55 lacks the anchoring capacity found in analogous BBIs, thus rendering the protein susceptible to hydrolysis. The inhibitory properties of LCTI, related to the simultaneous presence of two key amino acids (Gln18 and His54), render the molecule unusual within the natural Bowman–Birk inhibitor family.

Cloning, sequencing and expression in the seeds and radicles of two Lupinus albus conglutin γ genes

Two genes encoding conglutin gamma have been isolated from a Lupinus albus genomic library and sequenced. The expression of conglutin gamma was studied by partial amino acid sequencing of the mature seed protein and by nucleotide sequencing of reverse transcriptase-polymerase chain reaction products from various tissues during the plant life cycle.

Assessment of the tolerance to lupine-enriched pasta in peanut-allergic children

Background Reports of allergy to lupine derivatives (as de novo sensitization or cross‐reactivity in subjects allergic to peanut) are increasing as their use in food products increases.