PubMed Health⌕ Search

Biomedical subjects

J Mossé

Publications and source records attributed to J Mossé.

14 recordsLinked to original sources
PubMed1988

Model of a complex between the tetrahemic cytochrome c3 and the ferredoxin I from Desulfovibrio desulfuricans (Norway strain).

A three-dimensional model of an electron-transfer complex between the tetrahemic cytochrome c3 and the ferredoxin I from the sulfate-reducing bacterium Desulfovibrio desulfuricans (Norway strain) has been generated through computer graphics methods. The model is based on the known X-ray structure of the cytochrome and on a model of the ferredoxin that has been derived through computer graphics modeling and energy minimization methods, from the X-ray structure of the homologous ferredoxin from Peptococcus aerogenes. Four possible models of interaction between the two molecules were examined by bringing in close proximity each of the four hemes and the redox center (4Fe-4S) of the ferredoxin and by optimizing the ion pairs interactions. One of these models shows by far the "best" structure in terms of charges, interactions, and complementarity of the topology of the contact surfaces. In this complex, the distance between the iron atoms of the ferredoxin redox center and the hemic iron atom is 11.8 A, which compares well with those found between redox centers in other complexes. The contact surface area between the two molecules is 170 A2.

Amino Acid Sequence↗
PubMed1988

Variation of the amino acid scores and of the nitrogen-to-protein conversion factors in barley grain as a function of nitrogen content as compared with wheat and rye.

Barley grains (9 samples from 7 cultivars) with nitrogen contents (N) ranging from 1.45 to 4.01% of dry matter were analysed for their amino acid (AA) composition with high accuracy from six different hydrolysates per sample. AA levels in grain increased as linear functions of N with correlation coefficients close to unity. A comparison with literature data confirmed that the AA composition of any grain sample of normal barley can be predicted from its N for all phenotypes and genotypes. AAs in grain protein changed as hyperbolic functions of N which increased for Phe, Pro and Glx but more or less strongly decreased for the other AAs. By plotting AA scores against N, barley proteins were shown to be always richer than wheat and rye in Val and Phe + Tyr; sometimes richer than both other species for N less than 2 (Lys); 2.2 (Leu and Ile); 3.4 (Thr); sometimes intermediate to wheat and rye above the latter N values. They were also intermediate in sulphur AAs for N less than 1.9 and drastically poorer for N greater than 1.9. However, they were richer than both other species in Trp for N greater than 1.6. The hyperbolic variations of non-protein nitrogen and nitrogen-to-protein conversion factors were determined as a function of N and also compared with those of wheat and rye.

Amino Acids↗
PubMed1983

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.

Amino Acid Sequence↗
PubMed1982

The toxic fraction of gliadin digests in coeliac disease. Isolation by chromatography on Biogel P-10.

Improvement in the fractionation of gliadin digests and in the isolation of toxic fractions was achieved using chromatography on Biogel P-10. Fraction V, one of the 11 fractions eluted from a peptic-tryptic digest of crude gliadin extracted from Cappelle wheat, significantly affected coeliac jejunal mucosa in organ culture. BV, gamma V, omega V, the corresponding fractions V from beta-, gamma- and omega-gliadins, displayed similar toxic effects. Fraction VI containing peptides with a lower molecular mass did not show any significant cytotoxic activity and, moreover, inhibited the toxicity of fraction V. Analysis of the toxic fractions V showed that they contained peptides of 7-8,000 molecular mass, rich in proline and glutamine and poor in aromatic amino acids and carbohydrates. Among the various fractions, V, beta V from beta-gliadin appeared the less heterogeneous.

Amino Acids↗
PubMed1980

Isolation and characterization of beta-gliadin fractions.

beta-Gliadins of Cappelle wheat are distributed in three subsets in starch gel electrophoresis at pH 3.2, Six of these beta components have been isolated by sulfopropyl-Sephadex C-50 chromatography, gel filtration on Sephadex G-100 and sulfoethyl-cellulose chromatography. Apparent molecular weights determined by gel filtration and SDS-polyacrylamide gradient gel electrophoresis are between 29 000 and 35 000. Valine is the N-terminal amino acid of all beta-gliadins with the exception of the slowest component in electrophoresis at pH 3.2 the N-terminal amino acid of which is asparagine. The main difference between the amino acid compositions is the lack of tryptophan in the fastest of the three component subsets visible in electrophoresis at pH 3.2.

Amino Acids↗
PubMed1980

[Comparative toxicity of different cereals for subjects intolerant of gluten].

Coeliac disease is caused by prolamines, the storage proteins of some cereals, located in the endosperm. Cereals do not all have the same toxicity. The four wheat prolamine groups (alpha, beta, gamma and omega gliadins), visible in electrophoresis at acid pH, have been isolated and their toxicities compared by observing the morphological changes in intestinal biopsies cultured in vitro when peptic-tryptic digests of the studied proteins were added to the culture medium. The toxicity was found to be mainly located in the alpha and beta-gliadins and in peptides of 5 to 10 000 molecular weight. Peptides, resulting from peptic-tryptic hydrolysis, varied in length as a direct function of their proline content. In fact, peptide bond splitting by pepsin and trypsin is known to be blocked by proline. Thus, proline content determines peptide length and toxicity. Wheat, rye and barley toxicities were compared on the basis of a correlation between toxicity and the alpha- and beta-gliadin-like prolamine contents of these cereals. Electrophoretic estimation of alpha- and beta-gliadin-like prolamine content gave the following prediction of relative toxicity (in decreasing order): wheat, triticale, rye, barley and oats.

Amino Acids↗
PubMed1978

Heterogeneity of avenin, the oat prolamin. Fractionation, molecular weight and amino acid composition.

The prolamin, avenin, was extracted from oat seeds and shown to be maximally extractable in 45% (w/w) ethanol. A purification procedure is described and some properties of avenin are examined. As with wheat and barley prolamins, salt soluble and glutelin fractions were simultaneously extracted. Starch gel electrophoresis revealed two novel fractions, which were isolated by ion-exchange chromatography. These fractions have similar amino acid composition, threonine as the N-terminal amino acid and both have a 22 500 molecular weight. It is suggested that the avenin constituents have a common ancestral gene.

Amino Acids↗
PubMed1976

[Nature and fractionation of barley proteins extracted by ethanol, isopropanol and n-propanol in different proportions].

Barley alcoholsoluble protein extractabilities by aqueous ethanol, isopropanol and n-propanol were measured at room temperature. The quantities extracted by each alsohol strongly depend on the concentration of the alcohol. The most efficient concentration for the three alcohols were by increasing order: 45 per cent ethanol, 40 per cent isopropanol, 35 per cent (w/w) n-propanol. Hrodein preparations extracted by these three alcoholic solutions and by 75 per cent (w/w) ethanol were compared by means of the flour nitrogen percentage they contain and by electrophoresis, amino-acid analysis and Sephadex G 100 gel filtration. The preparations studied do not differ markedly in their amino-acid composition or electrophoretic pattern which shows at least 17 different bands. On the other hand, Sephadex G 100 gel filtration separates two main groups of proteins, The first one is present at the same level in all preparations studied and consists of electrophoretically typical hordeins (already described hordeins). The other group represents a fraction of the preparation, the more abundant as the solvent is more effective. This second group is excluded on Sephadex G 100 chromatography and does not give well defined bands by starch gel electrophoresis. Consequently it is related to some glutelins. Nevertheless its amino-acid composition is very close to the mean hordein composition. Electrophoretic comparison with glutelins extracted by acetic acid and with hordeins, all reduced and alkylated, discloses a great similitude between this fraction, the glutelins and some hordein fast components alpha, beta and gamma.

1-Propanol↗