Immunochemical crossreactivity between zein, hordein and gliadin

Antitumor Features of Vegetal Protein-Based Nanotherapeutics

The introduction of nanotechnology into pharmaceutical application revolutionized the administration of antitumor drugs through the modulation of their accumulation in specific organs/body compartments, a decrease in their side-effects and their controlled release from innovative systems. The use of plant-derived proteins as innovative, safe and renewable raw materials to be used for the development of polymeric nanoparticles unlocked a new scenario in the drug delivery field. In particular, the reduced size of the colloidal systems combined with the peculiar properties of non-immunogenic polymers favored the characterization and evaluation of the pharmacological activity of the novel nanoformulations. The aim of this review is to describe the physico-chemical properties of nanoparticles composed of vegetal proteins used to retain and deliver anticancer drugs, together with the most important preparation methods and the pharmacological features of these potential nanomedicines.

Isolation and characterization of a 20 kD prolamin from kodo millet (Paspalum scrobiculatum) (L.): homology with other millets and cereals

The homologus 20 kD prolamin from kodo millet and other minor millets viz. barnyard, little and foxtail millets, were purified using preparative gel electrophoresis and reversed phase high performance liquid chromatography (RP-HPLC). The amino acid composition of the purified 20 kD prolamin protein from different minor millets revealed higher content of glutamic acid, alanine, leucine and serine and lower quantity of lysine and methionine. They contain 55 to 58 percent of non-polar amino acids which make them more hydrophobic than other protein fractions. The total number of amino acid residues per polypeptide chain ranged from 152 to 155 based on theoretical calculation. Peptide mapping of the 20 kD prolamin hydrolyzed with trypsin gave fewer cleavage products than expected. The antigenic relationships among these minor millets and cereals viz. wheat, maize, rice, sorghum, finger millet and pearl millet were studied using the antibody raised against the 20 kD prolamin. Cross reactivity was seen in all the minor millets at the 20 kD region. But in barnyard and little millets lower molecular weight polypeptides also cross reacted with the antibody. Immunoblotting studies revealed that the prolamins from other cereals and millets are related to the 20 kD prolamin of kodo millet. Rice was the only common cereal that did not cross react immunologically with the antibody raised against 20 kD prolamin of kodo millet.

Evolutionary relationship of the members of the sulphur-rich hordein family revealed by common antigenic determinants

Five monoclonal antibodies raised against an enriched C hordein fraction have been characterized in detail and were found to be specific for the members of the sulphur-rich hordein family. Two antibodies specific for B hordein polypeptides were identified, one of which reacted predominantly with CNBr cleavage class III polypeptides. γ1 hordein was recognized by two antibodies, of which one also reacted with γ2 hordein and several members of the CNBr cleavage class II B hordein polypeptides. One antibody recognized γ3 hordein but cross-reacted at higher antibody concentration with almost all of the B and C hordein polypeptides. The specificity of the monoclonal antibodies was confirmed by Western blotting of one- or two-dimensionally separated hordein from the B hordein-deficient mutant hor2ca and its wild-type Carlsberg II and the γ3 hordein-deficient genotype Nevsky. The identification of the γ hordein-specific monoclonal antibodies was further supported by immune precipitation of in-vitro transcribed and translated γ2 hordein, and hor2ca and Carlsberg II mRNA translation products. The monoclonal antibodies were used to screen for mutants in γ hordein synthesis. Two mutants, one deficient in γ 1 hordein synthesis and a second in γ 2 or closely related B hordein polypeptides were identified. A model is proposed for the evolution of the sulphur-rich hordein loci Hor5 and Hor2.

Immunocrossreactivity of antisera against grain prolamines of wheat, rye, barley and oats

Prolamines extracted from wheat (gliadin), rye (secalin), barley (hordein) and oats (avenin) were used to raise antibodies in rabbits. The four prolamines were separated by SDS-PAGE and blotted onto nitrocellulose. The immunocrossreactivity of the separated prolamines with the four antisera was studied. The close botanical relationship between wheat and rye, and to a lesser extent barley, is clearly established. The crossreactivity of gliadin, secalin and hordein with anti-avenin serum was found to be weak. In contrast, avenin shows a strong crossreactivity with anti-gliadin serum.

The prolamin antibody reactivity against hordein polypeptides in sera from patients with coeliac disease

The antibody reactivity against the barley prolamin, hordein, was investigated by an immunoblotting technique, in sera from patients with untreated coeliac disease, patients with other gastrointestinal diseases and healthy controls. No characteristic hordein polypeptide antibody pattern could be connected to coeliac disease, as observed in a similar study using different fractions of the wheat prolamin, gliadin. Gliadin- and hordein-immunoadsorbent column experiments demonstrated that the prolamin reactivity originates from the same population of antibodies. It is speculated that distinct antigenic epitopes characteristic for untreated coeliac disease, might reside within a N-terminal repeat region of gliadin.

Antibodies to the photosystem I chlorophyll a + b antenna cross-react with polypeptides of CP29 and LHCII

A chlorophyll (a + b)--protein complex associated with photosystem I (PSI) was isolated from a larger PSI complex (CPIa) produced by electrophoresis of barley thylakoids solubilized with 300 mM octyl glucoside. It had an apparent Mr of 35,000-43,000 on 7.5% and 10% acrylamide gels respectively, and a chlorophyll a/b ratio of 2.5 +/- 1.5. Denaturation released four polypeptides migrating between 21-24 kDa. They were well separated from the polypeptides of the two photosystem II chlorophyll a + b antenna complexes: LHCII (25-27 kDa) and CP29 (28-29 kDa). In order to study the PSI antenna complex, antibodies were raised against highly purified CPIa. The antigen appeared to be pure when electrophoresed, blotted and reacted with its antiserum, i.e. anti-CPIa detected only the 64-66-kDa CPI apoprotein and the four 21-24 kDa antenna polypeptides. However, when blotted against the whole spectrum of thylakoid proteins, it cross-reacted with both LHCII and CP29 apoproteins. Removal of anti-CPI activity from the anti-CPIa did not affect these cross-reactions, showing that they were not due to antibodies directed against CPI. To show that the same antibody population was reacting with both the photosystem I and photosystem II antenna polypeptides, anti-CPIa was adsorbed onto highly purified CPIa on nitrocellulose. The bound antibody was eluted and used again in a Western blot against whole thylakoid proteins. This selected antibody population showed the same relative strength of reaction with photosystem I and photosystem II antenna polypeptides as the original antibody population had. Similar observations have been made with antibodies to the two photosystem II antenna complexes. We therefore conclude that there are antigenic determinants in common among the chlorophyll a + b binding polypeptides, and predict that there could be amino acid sequence similarities.

Immunochemical studies on barley seed storage proteins : The specificity of an antibody to 'C' hordein and its reaction with prolamins from other cereals

The antigenic relationships between the prolamins of barley, rye and wheat have been studied by examining the specificity of an antibody to 'C' hordein in a quantitative study using a laser nephelometer. The antibody reacts weakly with 'B' hordein and strongly with 75-kdalton and 40-kdalton γ-secalins from rye and γ3 some ω-gliadins from wheat. Absorption experiments and immunodiffusion tests indicate that there are shared antigenic determinants for most of the prolamins. All the species with reacting prolamins belong to the sub-family Festucoideae of the Gramineae. The prolamins of maize, pearl millet and sorghum, species of the sub-family Panicoideae, do not react. The results confirm the known lack of homology between the prolamins of the two sub-families and also indicate the presence of relationships not yet established between 'C' hordein, the 75-kdalton and 40-kdalton γ-secalins and also γ3 gliadin.

Subcellular localization of glutelin-2 in maize (Zea mays L.) endosperm

Accumulation of the 28 KD protein of the glutelin-(G2) fraction was followed in developing maize endosperm, using sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE) and peak integration of scanned gels. 28 KD glutelin-2 could already be observed from 15 days after pollination and its accumulates reached a plateau during the second half of the development period. The process of biosynthesis of 28 KD glutelin-2 and zeins occurs in a parallel way. Subcellular fractions obtained from linear sucrose gradient centrifugation of developing maize endosperms were analyzed by SDS-PAGE and immunoblotting using a serum reacting against glutelin-2 and 14 KD Z2. Glutelin-2 was found to be present in the protein bodies when subcellular fractionation was carried out without dithiothreitol (DTT). The presence of a reducing agent causes the elution of glutelin-2 from protein bodies. Immunocytochemical labelling using the protein A-colloidal gold technique in protein bodies incubated with anti-G2 IgG revealed that G2 is located mainly in the periphery of protein bodies. These results are interpreted as indicating a structural role for glutelins in protein bodies.

Secondary structure prediction of seed storage proteins

The comparison of partial primary structure of seed storage proteins leads to show homologies inside of each considered family (Legume seed legumins and cereal prolamins). Predicted secondary structures deduced from the presently known sequences also exhibit considerable homologies, which implies a severe conservatism of these proteins. Short repetitive segments of sequence of 5-20 residues are frequently occurring and give rise to the prediction either of beta-structure (or alpha-helix) bonded by beta-turns or of successive beta-turns. The latter conformation, which would be able to form a helicoidal arrangement, could contribute to a maximal packing of the protein molecules inside of the subcellular organelles (protein bodies) within which they are confined. As the only known function of seed storage proteins is to provide amino acids to the embryo, it is suggested that their ability to occupy a minimal volume is actually a reasonable explanation of their extreme conservatism in the course of evolution.

A simple and rapid dot-immunobinding assay for zein and other prolamins

A simple method for the immunochemical assay of zein and other prolamins is described. Alcohol-solubilized zein is spotted onto chromatography paper disks or strips, incubated with antiserum (30-60 min), washed with several changes of Tris-buffered saline (10 min), incubated with protein A-peroxidase (30 min), and washed with several changes of Tris-buffered saline (10 min). the binding of zein-specific antibody is visualized by peroxidase-catalyzed color production from 4-chloro-1-naphthol. The method is simple, inexpensive, and rapid (2 h total time) and has potential application to other insoluble antigens.