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V. Prakash - One of the best experts on this subject based on the ideXlab platform.

  • effect of sodium dodecyl sulfate acid alkali urea and guanidine hydrochloride on the circular dichroism of Alpha Globulin of sesamum indicum l
    International Journal of Peptide and Protein Research, 2009
    Co-Authors: V. Prakash, R K Nandi, B Jirgensons
    Abstract:

    The circular dichroic spectra of a-Globulin have been obtained under various solution conditions of sodium dodecyl sulfate, acid, alkali, urea and guanidine hydrochloride. The protein in phosphate buffer pH 7.4, 0 . 2 , h~a s about 25% bstructure and 5% a-helix, the rest being aperiodic or irregular structure. Sodium dodecyl sulfate induced more a-helical structure in the protein. The protein had nearly 20% a-helix at 1 x lo-= M SDS. At extreme acid or alkaline pH, the protein had no a-helix with Pstructure decreasing with further extremes of pH. The protein is represented by 100% aperiodic structure in 6.6 m urea and in 6.0 m guanidine hydrochloride solutions. The above results are discussed in view of some of the earlier results with regard to the association-dissociation and denaturation behavior of a-Globulin under various solution conditions.

  • dissociation and denaturation behaviour of sesame α Globulin in sodium dodecyl sulphate solution
    International Journal of Peptide and Protein Research, 2009
    Co-Authors: V. Prakash, P. K. Nandi
    Abstract:

    The effect ofanionic detergent, sodium dodecyl sulphate, on the majorprotein, Alpha-Globulin ofsesame seed(Sesamum indicum L.) has been investigated by geljiltration, sedimentation re!ocity, vi,rcosity, optical rotation, difference spectra and jluoresceuce measurements. The detergem causes dissociation of the protein first and then denaturation. In the deTergent concentration range of 1.75-4.0 x 10 - ~ M foul' components are observed in the ultracentrifuge. The specific rotation ofthe protein increases with the detergent concentration above 2.5 x 10 M and shows a cooperative transition between 3-8 x 10 M detergent suggesting conformational change; above 8 x 10 M detergent The value of - [Alpha] does not change. The reduced viscosity nred however, increases above 2.5 x 10- 3 M detergent and does not attain a plateau value. The difference spectrum ofthe protein indicates that both tryptophan and tyrosine groups have been affected by the detergent. The fluorescence intensity decreases and the maxima shifts towards red in the detergent solution resulting in an 'isoemissive point' at 355 nm. The double difference spectra in sucrose-detergent protein system show that below 5·0 x 10- 3 M detergent, the difference absorption andjluorescence spectrum result from the binding of the detergent near the chromophoric groups and are not due to conformational change. Binding studies by equilibrium dialysis indicate the presence of ~ 50 binding sites in the protein and a binding constant of 3.0 x 103

  • effect of succinylation on the functional and physicochemical properties of Alpha Globulin the major protein fraction from sesamum indicum l
    Nahrung-food, 2002
    Co-Authors: Magdy Zaghloul, V. Prakash
    Abstract:

    Alpha-Globulin the major protein fraction from Sesamum indicum was succinylated to different levels and the effect of the chemical modification was evaluated both on the functional and physicochemical properties. The results suggest that the pH of minimum solubility shifted to the more acidic side (pH approximately 4.5-5.5) for the succinylated Alpha-Globulin whereas for control Alpha-Globulin the pH of minimum solubility was 6.5. Succinylation also increased emulsion activity and emulsion stability of the protein. The emulsion stability increased from a control value of 53 +/- 3 s to a value of 122 +/- 5 s. Bulk density, water absorption capacity, oil absorption capacity, foam capacity and foam stability were evaluated in phosphate buffer (pH 7.0) containing 0.5 M sodium chloride and all these properties showed increased values as a result of succinylation. Ultracentrifugation studies showed that the % composition of 7S component increases with concomitant decrease in that of 11S fraction with the increase in percentage of succinylation. Further increase in succinylation resulted in only 2S component which is a dissociated form of 11S and/or 7S protein fractions. The fluorescence emission studies showed a decrease in the fluorescence emission intensity of Alpha-Globulin as a result of succinylation. The thermal stability of the protein molecule decreased due to progressive succinylation as indicated by decrease in the apparent thermal denaturation temperature from a control value of 84 to 62 degrees C at a succinylation level of 40%. These results suggest that succinylation improves the functional characteristics of Alpha-Globulin. Such changes in the functional properties have been attributed partly to the dissociation of the protein molecule at higher levels of succinylation and the increase in the net negative charge on the protein.

  • Kinetics and thermodynamics of the mechanism of interaction of sodium phytate with Alpha-Globulin.
    Biochemistry, 1993
    Co-Authors: S. Rajendran, V. Prakash
    Abstract:

    The precipitation mechanism of Alpha-Globulin in the presence of myo-inositol hexaphosphate (sodium phytate) was studied in detail. The maximum interaction was found at pH 2.3 where the protein was in a dissociated state having an 8.3S aggregate and a 1.5S monomer. This interaction was predominantly dependent upon the sodium phytate to protein ratio. Velocity sedimentation studies indicated polymer formation due to preferential progressive binding of ligand to polymer, whose size and concentration increased with an increase in sodium phytate concentration. The polymer formation was shown to be ligand mediated and exists independently in solution along with the monomer. The binding isotherm by equilibrium dialysis confirmed differential binding of sodium phytate to the polymer and the monomer as indicated by two sets of binding sites, one having 7 +/- 2 sites of a K value 1.3 x 10(-4) mol-1 and the other having 56 +/- 3 sites with a K value of 2.8 x 10(-3) mol-1. Binding resulted in perturbation of chromophores of protein due to charge effects. The kinetics of the polymer formation was shown to be a pseudo-first-order reaction having two steps. The initial fast reaction involving conformational changes has rate constants of k1 = 52.4 x 10(-3) s-1 and k' = 67.5 x 10(-3) s-1, followed by a slow reaction step of rate constants k2 = 4.3 x 10(-3) s-1 and k'2 = 2.9 x 10(-3) s-1 at sodium phytate concentrations of 1 x 10(-4) M and 5 x 10(-4) M, respectively.

Takahiro Adachi - One of the best experts on this subject based on the ideXlab platform.

  • characterization of a novel rice bzip protein which binds to the Alpha Globulin promoter
    Plant Molecular Biology, 1997
    Co-Authors: Masayuki Nakase, Naohito Aoki, Tsukasa Matsuda, Takahiro Adachi
    Abstract:

    Many plant basic leucine-zipper (bZIP) proteins have been isolated several of which have been shown to play a role in seed-specific gene expression. We isolated a novel bZIP protein (REB) gene encoding 425 amino acid residues from rice endosperm, which is similar to Opaque-2 heterodimerizing protein (OHP) of maize. The gene product, termed REB, contains Pro- and Gly-rich regions at its N terminus, followed by the typical basic and leucine-repeat regions. Recombinant REB binds to the region from -754 to -562 in the α-Globulin gene promoter, but not to promoters of other major storage genes such as glutelin, prolamin and albumin. The 5′ region of the α-Globulin gene possesses three binding sites for REB, which were determined as GCCACGT(A/C)AG, by using synthetic oligonucleotides. A Super-shift assay using anti-REB antibody suggested that REB is a major DNA-binding protein for the α-Globulin gene promoter in rice endosperm.

Jason T C Tzen - One of the best experts on this subject based on the ideXlab platform.

  • molecular cloning of 11s Globulin and 2s albumin the two major seed storage proteins in sesame
    Journal of Agricultural and Food Chemistry, 1999
    Co-Authors: Sorgan S K Tai, Emily C F Chen, Jason T C Tzen
    Abstract:

    Insoluble 11S Globulin and soluble 2S albumin, conventionally termed Alpha-Globulin and beta-Globulin, are the two major storage proteins and constitute 80-90% of total seed proteins in sesame. Two full-length cDNA clones were sequenced and deduced to encode sesame 11S Globulin and 2S albumin precursors, respectively. Deduced amino acid composition reveals that 2S albumin, but not 11S Globulin, is a sulfur-rich protein. Three abundant polypeptides of 50-60 kDa were resolved on SDS-PAGE when seed-purified 11S Globulin was prepared in nonreducing conditions. Immunological analysis suggests that these three polypeptides are encoded by homologous genes. Immunodetection on the overexpressed protein of the 11S Globulin clone in Escherichia coli indicates that this clone encodes the precursor protein of one of the three purified 11S Globulin polypeptides.

Masayuki Nakase - One of the best experts on this subject based on the ideXlab platform.

  • characterization of a novel rice bzip protein which binds to the Alpha Globulin promoter
    Plant Molecular Biology, 1997
    Co-Authors: Masayuki Nakase, Naohito Aoki, Tsukasa Matsuda, Takahiro Adachi
    Abstract:

    Many plant basic leucine-zipper (bZIP) proteins have been isolated several of which have been shown to play a role in seed-specific gene expression. We isolated a novel bZIP protein (REB) gene encoding 425 amino acid residues from rice endosperm, which is similar to Opaque-2 heterodimerizing protein (OHP) of maize. The gene product, termed REB, contains Pro- and Gly-rich regions at its N terminus, followed by the typical basic and leucine-repeat regions. Recombinant REB binds to the region from -754 to -562 in the α-Globulin gene promoter, but not to promoters of other major storage genes such as glutelin, prolamin and albumin. The 5′ region of the α-Globulin gene possesses three binding sites for REB, which were determined as GCCACGT(A/C)AG, by using synthetic oligonucleotides. A Super-shift assay using anti-REB antibody suggested that REB is a major DNA-binding protein for the α-Globulin gene promoter in rice endosperm.

John H. Griffin - One of the best experts on this subject based on the ideXlab platform.

  • Studies of Human Coagulation Factor XI and Its Complex With High Molecular Weight Kininogen
    2016
    Co-Authors: B. N. Bouma, Riek A. A. Vlooswijk, John H. Griffin
    Abstract:

    Coagulation factor Xl was purified from human plasma using ion-exchange chromatographyand affinity chromatography on high molecular weight kininogen-Sepharose. monospecific precipitating antiserum was prepared and used to study factor Xl antigen. Factor Xl did not migrate during electrophoresis at pH 8.3. High molecular weight kininogen (HMWK), an Alpha Globulin, reversibly associates with factor Xl. Complex formation between HMWK and factor Xl was observed under conditions of crossedimmunoelectrophoresis. Using Laurell rocket immunoelec