Jacques Landry

Influence of the protein distribution of maize endosperm on ruminal starch degradability.

This study was aimed at determining the influence of the protein distribution of maize endosperm on ruminal starch degradation using 14 maizes differing in endosperm texture (eight dent and six flint maizes). Ruminal starch degradability was determined by an in situ technique on ground samples with a particle size of 3 mm. The distribution of endosperm proteins was assayed by a method based on their differential solubilities in solvents. The (α,β,δ)-zeins and the true glutelins were the predominant proteins in the endosperm. The (α,β,δ)-zeins (66.1 and 70.1 g kg−1 of recovered protein for dent and flint types respectively) and the true glutelins (21.8 and 18.4 g kg−1 of recovered protein for dent and flint types respectively) were related to the vitreousness, ie the ratio of vitreous to floury endosperm. Ruminal starch degradability averaged 619 and 462 g kg−1 for dent and flint maizes respectively. It was correlated negatively with the (α,β,δ)-zeins and positively with the true glutelins. The (α,β,δ)-zeins located in the protein bodies should limit the accessibility of starch granules to ruminal micro-organisms and, as a consequence, the ruminal starch degradability. © 2000 Society of Chemical Industry

Genetic control of lysine metabolism in maize endosperm mutants

The capacity of three maize endosperm opaque mutants (o10, o11 and o13) to accumulate soluble lysine in the seed in relation to their wildtype counterpart, W22+, was investigated. The W22o13 and W22o11 mutants exhibited 278% and 186% increases in soluble lysine, respectively, while for W22o10, a 36% decrease was observed, compared with the wildtype. A quantitative and qualitative study of the N constituents of the endosperm has been conducted and data obtained for the total protein, non-protein N, soluble amino acids, albumins / globulins, zeins and glutelins present in the seed of the mutants. Following 2D-PAGE, a total of 38 different forms of zein polypeptides were detected and considerable differences were noted between the three mutant lines. The metabolism of lysine was also studied by analysis of the enzymes aspartate kinase, homoserine dehydrogenase, lysine 2-oxoglutarate reductase and saccharopine dehydrogenase, which exhibited major changes in activity, depending on the genotype, suggesting that the mutant genes may have distinct regulatory activities.

Improved Method for Isolating and Quantitating α-Amino Nitrogen as Nonprotein, True Protein, Salt-Soluble Proteins, Zeins, and True Glutelins in Maize Endosperm

ABSTRACT The conventional Landry-Moureaux method for selective extraction of maize proteins was modified by reducing the contact time of meal with extractants and by removing 55% 2-propanol as extractant. The new procedure, coupled with a method for quantitating protein at microgram level, was used for assessing the nitrogen distribution of four soluble protein fractions present in 100-mg samples of endosperm originating from six maize inbreds and opaque-2 versions. Proteins extracted with 55% 2-propanol plus reductant were made up of α-, β-, γ-, and δ-zeins. Proteins extracted subsequently with salt plus reductant were minor and poor in lysine (1 mol%).They were associated with zeins. Comparison of present data with those available in the literature showed a close similarity for a given genotype between the percentage of total α-amino nitrogen extracted by 2-propanol plus reductant than by salt plus reductant under conditions of the modified procedure and that of total Kjeldhal nitrogen extracted by 2-pr...

Protein distribution pattern in floury and vitreous endosperm of maize grain

ABSTRACT Alpha-amino nitrogen compounds of floury and vitreous parts of hand-dissected endosperm from eight maize (Zea mays L.) inbred lines, representing a broad range of vitreousness (42–95%), were isolated as nonprotein nitrogen, albumin-globulins, zeins, and true glutelins. The three protein classes averaged, respectively, 13, 48, and 35% of total nitrogen in floury endosperm, and 4, 79, and 15% of that in vitreous endosperm. For six inbreds, floury endosperm was richer in 27 kDa γ-zein than vitreous endosperm; the reverse was found for an Argentine flint inbred (ARGL 256), and only traces of 27 kDa γ-zein occurred in both floury and vitreous endosperm of inbred F113. Results were compared with protein distribution patterns reported in the literature of whole endosperm of wild-type and mutant genotypes of maize, and with wild relatives of maize, Tripsacum, and teosintes. When percentage of salt-soluble nitrogen increased from 2% (Tripsacum) to 22% (in double mutant Oh43o2;bt2), zeins decreased from 87...

Distribution and amino acid composition of protein fractions in opaque-2 maize grains

Abstract Immature opaque 2 ( o 2) maize grains were compared with mature grains of o 2 and normal maizes to determine the distribution and amino acid composition of protein fractions isolated by selective extraction. All the fractions are accumulated in o 2 grains on development, except the albumins whose concentration decreases in the last stage of maturation. Each fraction has a nearly constant amino acid composition which is similar to that of the corresponding fractions present in normal grains. The data confirm that the main effect of the o 2 gene is to alter the distribution of protein fractions by decreasing the proportion of accumulated zein and by increasing the proportions of salt-soluble proteins and G 3 -glutelins.

Zein of maize grain: I — isolation by gel filtration and characterization of monomeric and dimeric species

Unreduced zein chromatographed on Sephadex G 200 in 8 M urea, on G 100 in 1.5 or 2.5% sodium dodecyl sulfate (SDS) and on hydroxypropylated G 100 in 70% ethanol was resolved into two minor fractions A and B and two major ones D and M irrespective of the medium. The quantitative importance of the fraction M was dependent on the isolation conditions of zein. It decreased from 53% of the proteins contained in ethanolic extract and chromatographed as they were extracted, to 40% of the purified zein. The molecular weight values obtained from SDS-polyacrylamide gel electrophoresis and amino acid compositional data indicated that fractions D and M, as isolated from purified zein in the presence of ethanol, represented respectively dimeric and monomeric forms of a mixture of Mr 22 000 and 24 000 polypeptides with threonine or phenylalanine as NH2-terminal residue. Electrophoretic analysis of selectively carbamylated fraction M on starch gel at pH 3.5 revealed that zein subunits comprised several polypeptides differing in the number and the nature of basic amino acids. At least one of these polypeptides contained one lysyl residue.

RECENT RESEARCH ON MAJOR MAIZE PROTEINS: ZEINS AND GLUTELINS

Several authors have reviewed the different kinds of problems concerning seed proteins with more or less attention devoted to maize ones. We just mention some of them. From a biochemical point of view, a few papers treat of whole cereal proteins : Waldschmidt-Leitz and Metzner (1962), Wall (1964), Mossé (1968) and Inglett (1977). Other ones deal only with cereal prolamins (Mossé, 1966) or glutelins (Dimler, 1966) or even zein (Mossé, 1961). The most recent and completed one of Wall and Paulis (1978) concerns maize and sorghum proteins. From structure and localization point of view, Inglett (1970) reviews our knowledge on maize grain. Ory (1972) , Mascherpa (1975), Miège (1975b), Briarty (1978) and Pernollet (1978) discuss protein bodies. From a physiological point of view, Miège (1975c) considers seed development and Miège (1975d) , Ashton (1976) and Tomos and Laidman (1979) analyze germination and storage mobilization processes. From a genetic point of view. Nelson (1969) , Mertz (1972), Nelson and Burr (1973), Kaul (1973), Mossé (1978), Röbbelen (1979) and Thomson and Doll (1979) treat of plant breeding, particularly for better protein quantity and quality, while Mossé (1973) analyzes the nature and origin of plant protein heterogeneity and polymorphism. Such a polymorphism indeed enables the use of storage proteins as genetic markers in

A linear model for quantitating the accumulation of zeins and their fractions (α+δ, β&γ) in developing endosperm of wild-type and mutant maizes

Abstract A model based upon the occurrence of a linear relationship between the amounts of zeins and total proteins present in developing maize endosperm was applied to some data of the literature. Those were concerned with grains of W64A, Illinois high and low protein (IHP and ILP) cultured in vivo and in vitro together with in vivo grown grains of opaque-2 ( o2 ) and Mucronate ( Mc ) mutants, and Mco2 double mutant. The relative rate of zein accumulation, corresponding to the slope of a straight line, was found to be insensitive to environmental factors. It was assessed to 0.217, 0.431, 0.490, 0.598 and 0.799 for Mco2 , ILP, o2 , W64A and IHP maizes, respectively. The same type of relationship was tested between the amounts of zein fractions (α+δ, β and γ) and total zeins present in developing endosperm of three genotypes. The relative accumulation rate for a given fraction was very close to its proportion determined from mature endosperm irrespective of the genotype. According to the sign of y -intercept γ-zeins were found to be synthesized prior to (α+δ)-zeins, in agreement with the analysis of protein bodies using immuno-localisation; β-zein was synthesized after (α+δ)-zeins, contrary to the findings of immuno-localisation experiments, suggesting two different accumulation rates for this fraction.

Protein distribution in gluten products isolated during and after wet-milling of maize grains

ABSTRACT The protein distribution in five gluten samples isolated during and after wet-milling of maize grains (slurry before and after filtration, total industrial gluten meal, and coarse and fine fractions obtained after sieving) was investigated by sequential extraction. Six fractions (FI-FVI), including residue, were isolated. Heating filtered slurry to draw water away did not alter protein distribution. Compared with values reported in the literature for endosperm protein, we found a decrease in FI and FIV, respectively, extracted with salt alone and with reductant, due to proteolysis and partial elimination of nonprotein nitrogen during slurry filtration, and an increase in FII and decrease in FIII, alcohol-soluble proteins extracted without and with reductant, respectively, due to the presence of SO2 in the steeping liquor. Gluten, with respect to the endosperm from which it originated, was richer in zeins (FII + FIII) and glutelins (FV + FVI) due to partial removal of salt-soluble proteins (FI + F...

Zein of maize grain: II — the charge heterogeneity of free subunits

The subunits present as monomers in unreduced zein and isolated as fraction M by gel filtration, were chromatographed on sulfoethyl-cellulose. Three major subfractions were detected and characterized. Each of them, submitted to electrophoresis at pH 3.5, migrated as a single band corresponding to each of the three major electrophoretic forms seen in fraction M at the same pH. The presence of lysine in some polypeptides, suggested by amino acid composition data, was confirmed by electrophoretic analysis of carbamylated subfractions at pH 3.5. At pH 8.9 each subfractions was further resolved into three cationic bands in starch gel and three (or more) anionic bands in polyacrylamide gel. The same fractionation was also obtained by submitting the major electroforms of fraction M, as isolated at pH 3.5, to isoelectric focusing. Based on these observations, the most probable distributions of basic amino acids in subunits detected by electrophoresis at pH 8.9 were specified and compared to those recently published for several zein clones. The presence per polypeptide chain of three carboxyl groups and occasionally of one lysine would be a feature of zein originating from maize hybrid Inra 260.