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PubMed1999

Coeliac disease in the year 2000.

Coeliac disease is a permanent intolerance to wheat gliadins and related prolamines. Patients who have an obvious malabsorption syndrome form only a small minority of the total number of people with coeliac disease. There are, in fact, no pathognomonic clinical features, and the condition is defined and diagnosed by the presence of pathological changes in the small bowel mucosa related to the presence of toxic prolamines. Susceptibility to coeliac disease is determined to a significant extent by genetic factors. A large part of the genetic susceptibility maps to the HLA region on chromosome 6, as approximately 95% of coeliac disease patients carry an almost identical HLA DQ2/heterodimer; a role of non-HLA genes has also been postulated. From a pathogenetic point of view, most evidence supports the notion of a DQ-restricted gluten-specific Th1 response in the lamina propria; nonetheless, it is possible that, in coeliac subjects, gluten, prior to T cell activation, could exert a direct toxic effect leading to the production of proinflammatory signals.

Celiac Disease↗

PubMed2005

Identification of LMW glutenin-like genes from Secale sylvestre host.

Three low-molecular-weight (LMW) glutenin-like genes (designated as Ssy1, Ssy2 and Ssy3) from Secale sylvestre Host were isolated and characterized. The three genes consist of a predicted highly conservative signal peptide with 20 amino acids, a short N-terminal region with 13 amino acids, a highly variable repetitive domain and a less variable C-terminal domain. The deduced amino acid sequences of the three genes were the LMW-m type due to a methionine residue at the N-terminus. The phylogenic analysis indicated that the prolamin genes could be perfectly clustered into five groups, including HMW-GS, LMW-GS, alpha/beta-, gamma- and omega-prolamin. The LMW glutenin-like genes of S. sylvestre were more orthologous with the LMW-GS genes of wheat and B hordein genes of barley, which also had been confirmed by the homology analysis with the LMW-GS of wheat at Glu-A3, Glu-B3 and Glu-D3 loci. These results indicated that a chromosome locus (designated as Glu-R3) might be located on the R genome of S. sylvestre with the functions similar to the Glu-3 locus in wheat and its related species.

Amino Acid Sequence↗

PubMedDate not supplied

[Biochemical and molecular characterization of gliadins].

Gliadins account for about 40-50% of the total proteins in wheat seeds and play an important role on the nutritional and processing quality of flour. Usually, gliadins could be divided into alpha- (alpha/beta-), gamma- and omega-groups, whereas the low-molecular-weigh (LMW) gliadins were novel seed storage proteins. The low-molecular-weight glutenin subunits (LMW-GSs) were also designated as gliadins in a few literatures. The genes encoding gliadins were mainly located on the short arms of group 6 and group 1 chromosomes, and not evenly distributed. Repetitive sequences covered most of un-coding regions, which attributed greatly to the evolution of wheat genome. Primary structure of each gliadin has been divided into several domains, and the long repetitive domains consisted of peptide motifs. Conserved cysteine residues mainly formed intramolecular disulphide bonds. The rare potential intermolecular disulphide bonds and the long repetitive domains played an important role in the wheat flour quality. There was a general idea that gliadin genes, even prolamin genes, have a common origin and subsequent divergence lead to the gene polymorphism. The gamma-gliadins have been considered to be the most ancient of the wheat prolamin family. Several elements in the 5'-flanking (e.g. CAAT and TATA box) and the 3'-flanking sequences had been detected, which had been shown necessary for the proper expression of gliadins.

Evolution, Molecular↗

PubMed1989

[Protection of the pancreatico-digestive anastomosis following resection of the head of the pancreas by pancreatic duct occlusion with fibrin (-glue). Animal experiment and clinical experiences].

The pancreatico-digestive anastomosis is especially then endangered by dehiscence when, following resections due to carcinomas, a healthy lienal pancreatic rest has to be connected to the intestine. In the last years the pancreatic duct occlusion (PDO) with Prolamin proved to be possible for the elimination of the disturbing exocrine secretion. Apart from a strong exocrine fibrosis, a deterioration of the endocrine function results too. In animal experiments as well as clinically a simple and effective method for the protection of the pancreatico-digestive anastomosis could be developed by PDO with fibrin sealant (FS). Contrary to PDO with Prolamin a lower-grade, interstitial fibrosis under intact exocrine function is caused due to the short, 6 days at the most lasting blockade of the exocrine pancreatic secretion. Because of the high tryptic activity of the pancreatic juice 20,000 IU/ml Aprotinin were added to the fibrin sealant. So far this method was employed successfully in 36 patients within the scope of Whipple's operations due to pancreatic head carcinomas.

Ampulla of Vater↗

PubMed1987

Pancreas transplantation. An immunohistologic and histopathologic examination of 100 grafts.

The authors examined tissues obtained by biopsy, pancreatectomy, and autopsy from 100 pancreas grafts to determine the cause of dysfunction or failure of the graft. Immunohistologic examination of 42 tissues to determine the mononuclear cell phenotypes and Class I and II antigen expression was performed as well. Technical factors--infections, thrombosis, obstruction--accounted for a large number of graft losses, but immunologic-mediated mechanisms resulted in graft dysfunction and failure as well. Pleomorphic inflammatory infiltrates were present in grafts with acute rejection, as well as Silastic and Prolamine duct-obstructed grafts. Criteria useful in the identification of acute rejection from pancreatitis included a more intense, predominantly mononuclear cell infiltration of transformed lymphocytes in the exocrine pancreas and evidence of vascular rejection--endovasculitis or fibrinoid necrosis. Increased expression and/or induction of Class I and II antigens on pancreatic constituents occurred in grafts with evidence of acute rejection, but also with Silastic and prolamine duct-obstructed pancreatitis. An isletitis occurred in 25% of the grafts. Nine of the 25 grafts (36%) with isletitis also had selective loss of beta cells from the islets. Recurrent diabetes mellitus appeared to have developed in these cases, which accounted for loss of graft function.

Biopsy↗

PubMedDate not supplied

[Study of the biological value of rice groats proteins].

The content of essential amino acids in the total rice protein and its fractions was determined; the degree to which the in vitro protein and starch are liable to be charged by enzymes was studied and also the biological value of the total protein and its fractions underwent appraisal by using the Tetrahymena pyriformis W. as a test organism. As to the amino acids content the protein fractions differ from one another, with lysine level in albumin amounting to 4.07, globulin--2.46, prolamine--0.88 and gluteline--3.15 per cent. Because of a low prolamine content of 1.9 per cent, the biological value of rice is greater than that of other cereals. Following heat treatment the lysine and methionine levels go down by 7 and 6 per cent, respectively, while the degree of the proteins and starch hydrolysis---increases. The hydrolysis of starch forming part of the milled rice results in a greater accessibility of proteins to the action of proteolytic enzymes. The relative nutritional value correlates with the lysine content.

Amino Acids↗

PubMed1986

Amino acid composition of some Amaranthus sp. grain proteins and of its fractions.

This study was carried out to determine the protein content of several Amaranthus sp. grains. Findings revealed this has a high lysine (5.3 to 6.3 of the protein) and sulphur amino acids content (3.4-4.0%), while leucine could well be limiting when those seeds are used as a sole protein source in food. Using the correction for in vitro protein digestibility, the chemical score varied from 50 to 67. The calculated protein efficiency ratios and biological values ranged from 1.39 to 1.80 and 53 to 68, respectively. Considering that amaranth grain is a good supplement to cereal grain, the protein of A. hypochondriacus HH5 (yellow seeds) and A. anclancalius (black seeds) was fractionated into albumin, globulin, prolamin and glutelin. The average proportions between those soluble proteins were 65:17:11:7, respectively. Albumin had the highest lysine content (7.3-8.2%), and globulin the highest methionine (4.1-5.3%) and phenylalanine (6.0-6.1%) content. Prolamin had the highest threonine (4.6-5.4%) and leucine (6.8-6.9%) content, while glutelin had a very low methionine content (0.6-1.0%). Based on the above-mentioned findings, the authors conclude the variation in the amino acid composition of the protein fractions can be used for genetic protein improvement.

Amaranthus↗

PubMed1981

Segmental pancreas transplantation from living related and cadaver donors: a clinical experience.

Between July 25, 1978, and January 25, 1981, 20 segmental pancreas transplants from 14 cadaver (cad) and six related (rel) donors were performed. All but two recipients had previously received renal allografts for treatment of end-sage diabetic nephropathy. The grafts were placed intraperitoneally-13 with open ducts, 4 with prolamine-injected ducts, and 3 with silicone rubber-injected ducts. At this writing six patients have functioning grafts (3 silicone, 3 open duct) at less than 1 (cad), 2 (cad), 3 (rel), 15 (cad), 20 (rel), and 31 (cad) months. Five open-duct grafts failed for technical reasons. Two prolamine-injected grafts lost function between 1 and 3 months; biopsy specimens showed severe fibrosis. The others lost function between 2 and 4 months. Three patients died 1 to 3 months after transplantation. Metabolic test results were normal or nearly normal in most recipients with functioning grafts. Splenectomy was required in one related donor; there were no other complications of donation. Technical problems and rejection are impediments to application of pancreas transplantation, but a sustained correction of the metabolic defect has been achieved in a few patients, and the effect on secondary complications are studied.

Adolescent↗

PubMed1982

Wheat gliadin fractions and other cereal antigens reactive with antibodies in the sera of coeliac patients.

The mixed reverse solid phase passive antiglobulin haemadsorption test (MRSPAH) and the enzyme linked immunosorbant assay (ELISA) were found equally sensitive and fitted for the measurement of serum IgG antibodies against alcohol soluble gliadins. Using the ELISA method, three coeliac sera with elevated antibody titres against gliadins and two control sera with low titres were tested for IgG antibodies against the main groups of wheat proteins (acetic acid soluble glutenins, salt soluble albumins and globulins and alcohol soluble gliadins), eight fractions of gliadin and the alcohol soluble proteins of barley, rye, oat, maize and rice. As rice contained little alcohol soluble protein, a test against acid soluble rice proteins was included. In all three patient sera, titres higher than or equal to that for crude gliadin were found for wheat glutenin and for gliadin fractions seven and eight, both containing alpha gliadins. Similar high titres were found when these coeliac sera were tested against rye, barley and oat prolamines. Maize prolamines gave only low titres and no antibodies could be detected against rice proteins, in line with the tolerance of these latter two cereals by patients with coeliac disease. It would appear that sera from coeliac patients react with more than one antigenic fraction of protein in wheat and other cereals. Also sera from two normal persons appeared to have the same spectrum of reactivity against these cereal proteins as did the three sera from coeliac patients. The titres in normal sera were however much lower.

Antigens↗

PubMed1994

Celiac disease and the spectrum of gluten sensitivity.

Celiac disease is a well-known entity in which intolerance to wheat gluten and related proteins from barley, rye, and oats (collectively known as prolamins) damage intestinal mucosa. New insights into the pathology of the celiac intestinal lesion point to a wider spectrum of gluten sensitivity than previously thought. Recent advances in immunology and genetics have shed light on the underlying mechanisms and risks associated with the disease. Although the classical manifestations are well known, the wide variety of clinical presentations make celiac disease often difficult to diagnose, and the ubiquitous presence of prolamins in the Western diet make treatment challenging.

Celiac Disease↗

PubMed1998

Deposition of storage proteins.

Plants store amino acids for longer periods in the form of specific storage proteins. These are deposited in seeds, in root and shoot tubers, in the wood and bark parenchyma of trees and in other vegetative organs. Storage proteins are protected against uncontrolled premature degradation by several mechanisms. The major one is to deposit the storage proteins into specialized membrane-bounded storage organelles, called protein bodies (PB). In the endosperm cells of maize and rice prolamins are sequestered into PBs which are derived from the endoplasmic reticulum (ER). Globulins, the typical storage proteins of dicotyledonous plants, and prolamins of some cereals are transported from the ER through the Golgi apparatus and then into protein storage vacuoles (PSV) which later become transformed into PBs. Sorting and targeting of storage proteins begins during their biosynthesis on membrane-bound polysomes where an N-terminal signal peptide mediates their segregation into the lumen of the ER. After cleavage of the signal peptide, the polypeptides are glycosylated and folded with the aid of chaperones. While still in the ER, disulfide bridges are formed which stabilize the structure and several polypeptides are joined to form an oligomer which has the proper conformation to be either deposited in ER-derived PB or to be further transferred to the PSV. At the trans-Golgi cisternae transport vesicles are sequestered which carry the storage proteins to the PSV. Several storage proteins are also processed after arriving in the PSVs in order to generate a conformation that is capable of final deposition. Some storage protein precursors have short N- or C-terminal targeting sequences which are detached after arrival in the PSV. Others have been shown to have internal sequence regions which could act as targeting information. In some cases positive targeting information is known to mediate sorting into the PSV whereas in other cases aggregation and membrane association seem to be major sorting mechanisms.

Amino Acid Sequence↗

PubMed1993

Isolation of amaranth flour proteins by fractionation procedures and sonication.

The use of whole and defatted amaranth flour for protein isolation of Osborne fractions is described. Extractability of prolamins, the minor fraction, increased from 2.8 to 5% by adding a reducing agent. Glutelins proved to be poorly solubilized (3.3%) in dilute acetic acid, but they reached a high solubility value (40.8%) using a borate buffer in the presence of a reducing agent and a detergent; solubility remarkably declined without the latter two chemicals. Sonication (a fast and simple technique) in the presence of a detergent proved to be more efficient, compared with stirring, for extractability of total unreduced proteins.

Albumins↗

PubMed1991

[Analysis of food and feed by partial sequences of characteristic protein components (carrier peptides). 1. Isolation and structural determination of wheat-specific peptides from chymotryptic hydrolysates of gliadin].

Gliadins from wheat flour were extracted with 70% aqueous ethanol and hydrolyzed with alpha-chymotrypsin. Eight peptides, which seemed adequate as specific indicators for wheat ('Leitpeptide'), were isolated from the partial hydrolysate by RP-HPLC and analyzed for their amino acid sequences. Six of them were attributed to gliadin sequences already described in the literature, whereas two peptides represented novel sequence variations. Parallel investigations on the corresponding partial hydrolysates of prolamins from rye, barley, oats and maize showed that the isolated peptides were specific for wheat. A search in the protein data bank MIPS X (as of January 23 rd, 1990) did not produce any identical sequence. The 'Leitpeptide' allows the sensitive and specific recognition of wheat in complex and heated systems by RP-HPLC. They could be used also as the basis for immunochemical tests which would be convenient in routine analysis.

Amino Acid Sequence↗

PubMed1991

Seed protein fractions and amino acid composition in gram (Cicer arietinum).

Six chickpea strains were analysed for their protein content and various protein fractions. The protein content ranged from 20.9-25.27%. Albumin, globulin, prolamin and glutelin contents ranged from 8.39-12.31%; 53.44-60.29%; 3.12-6.89% and 19.38-24.40% respectively. Salt soluble proteins (albumin + globulin) and globulins resolved into 19-23 bands whereas albumin proteins resolved into 30-34 bands. The molecular weights of various polypeptides ranged from 10-91 kD. Amino acid analysis of total proteins revealed that glutamic acid was present in maximum concentration followed by aspartic acid and arginine. Just like other pulse proteins, chick pea proteins were also found deficient in sulphur containing amino acids.

Albumins↗

PubMed2005

The methylation cycle and its possible functions in barley endosperm development.

Barley endosperm development can be subdivided into the pre-storage, intermediate, storage and desiccation phase. Nothing is known about DNA methylation events involved in different endosperm-specific developmental programmes. A complete set of methylation cycle enzyme genes was identified and investigated by mRNA expression analysis. During the pre-storage phase, methionine synthase and S-adenosylmethionine (AdoMet) synthase genes are expressed at high levels, mainly to produce AdoMet, which might be used for methylation processes as indicated by high expression of methyltransferases HvMET1, HvCMT1 and HvDnmt3-1 as well as AdoHcy hydrolase genes. The methyltransferases, core histones and DNA-unwinding ATPases are co-expressed at the mRNA level. On the contrary, storage protein (prolamin) gene expression is repressed due to CpG methylation. Expression of genes responsible for starch biosynthesis is also developmentally regulated but not methylation-dependent. Thus, during pre-storage phase, activity of HvMET1 and HvCMT1 possibly maintains DNA replication and suppresses specific pathways of maturation. Besides, HvDnmt3-1 might be responsible for differentiation-specific de novo methylation. Expression of methyltransferases HvDnmt3-2 and HvCMT2 peaks during the onset of massive starch accumulation. The enzymes are likely responsible for DNA methylation involved in determining plastid division and amyloplast differentiation as concluded from the patterns of co-expressed genes. Levels of AdoMet decarboxylase mRNA, but not methyltransferase- and AdoHcy mRNA, increase at the beginning of desiccation together with methionine synthase and AdoMet synthase levels. This increase may be indicative for utilization of AdoMet in polyamine production protecting aleuron and embryo cell membranes during desiccation.

Adenosine Triphosphatases↗

PubMed2006

Cloning and characterization of four B-hordein genes from Tibetan hull-less barley (Hordeum vulgare subsp. vulgare).

Four B-hordein genes, designated BH1-BH4, were cloned using PCR amplification from two hull-less barley cultivars, ZQ7239 and ZQ148, collected from Tibet. The results of sequencing indicated that BH1-BH4 contained complete open reading frames (ORFs). Comparison of their predicted polypeptide sequences with the published sequences suggested that they all share the same basic protein structure. Phylogenetic analysis indicated that the deduced amino-acid sequences of BH1-BH4 genes were more closely related to B-hordeins from cultivated barley (Hordeum vulgare L.) than to any other prolamins from wild barley and Aegilops tauschii. Comparison of the coding regions of BH1-BH4 genes showed that BH1 had a lower sequence identity to other previously published B-hordeins than the other three B-hordeins obtained in this study. BH1 was then cloned in a bacterial expression vector based on bacteriophage T7 RNA polymerase. The resulting plasmid produced a 28.15 kDa protein in Escherichia coli. The potential value of B-hordein genes in grain quality improvement of hull-less barley has been discussed.

Cloning, Molecular↗

PubMed2003

Solution structure of RicC3, a 2S albumin storage protein from Ricinus communis.

The three-dimensional structure in aqueous solution of recombinant (15)N labeled RicC3, a 2S albumin protein from the seeds of castor bean (Ricinus communis), has been determined by NMR methods. The computed structures were based on 1564 upper limit distance constraints derived from NOE cross-correlation intensities measured in the 2D-NOESY and 3D-HSQC-NOESY experiments, 70 phi torsion angle constraints obtained from (3)J(HNH)(alpha) couplings measured in the HNHA experiment, and 30 psi torsion angle constraints derived from (3)J(H)(alpha)(Ni+1) couplings measured in the HNHB experiment. The computed structures showed a RMSD radius of 0.64 A for the structural core. The resulting structure consists of five amphipatic helices arranged in a right-handed super helix, a folding motif first observed in nonspecific lipid transfer proteins. Different than the latter, RicC3 does have not an internal cavity, a fact that can be related to the exchange in the pairing of disulfide bridges in the segment.CXC. Previous attempts to determine high resolution structures of a 2S albumin protein by either X-ray crystallography or NMR methods failed because of the heterogeneity of the protein prepared from natural sources. Both 2S albumins and nonspecific lipid transfer proteins belong to the prolamine superfamily, some of whose members are food allergens. The solution structure for recombinant RicC3 determined here is a suitable representative structure for the broad family of seed 2S albumin proteins, which may help to establish meaningful relationships between structure and allergenicity. RicC3 is also the peptidic component of the immunomodulator Inmunoferon, a widely used pharmaceutical product, and its structure is expected to help understand its pharmaceutical activity.

2S Albumins, Plant↗

PubMed2004

Solution structure of a methionine-rich 2S albumin from sunflower seeds: relationship to its allergenic and emulsifying properties.

The three-dimensional structure in aqueous solution of SFA-8, a 2S albumin 103-residue protein from seeds of sunflower (Helianthus anuus L.), has been determined by NMR methods. An almost complete (1)H resonance assignment was accomplished from analysis of two-dimensional (2D) COSY and 2D TOCSY spectra, and the structure was computed by using restrained molecular dynamics on the basis of 1393 upper limit distance constraints derived from NOE cross-correlation intensities measured in 2D NOESY spectra. In contrast with most other 2S albumins, SFA-8 consists of a single polypeptide chain without any cleavage in the segment of residues 30-46. The computed structures exhibited an rmsd radius of 0.52 A for the backbone structural core (residues 11-30 and 46-101) and 1.01 A for the side chain heavy atoms. The resulting structure consists of five amphipathic helices arranged in a right-handed superhelix, a folding motif first observed in nonspecific lipid transfer (nsLTP) proteins, and common to other 2S albumins. In contrast to nsLTP proteins, neither SFA-8 nor RicC3 (a 2S albumin from castor bean) has an internal cavity that is able to host a lipid molecule, which results from an exchange in the pairing of disulfide bridges in the CXC segment. Both 2S albumins and nonspecific lipid transfer proteins belong to the prolamin superfamily, which includes a number of important food allergens. Differences in the extension and solvent exposition of the so-called "hypervariable loop" (which connects helices III and IV) in SFA-8 and RicC3 may be responsible for the different allergenic properties of the two proteins. SFA-8 has been shown to form highly stable emulsions with oil/water mixtures. We propose that these properties may be determined partly by a hydrophobic patch at the surface of the protein which consists of five methionines that partially hide the Trp76 residue. The flexibility of the loop which contains Trp76 and the hydrophobicity of the whole environment may favor a conformational change, by which the Trp76 side chain may become inserted into the oil phase.

2S Albumins, Plant↗