ISOLATION AND CHARACTERIZATION OF AMARANTIN, THE 11S AMARANTH SEED GLOBULIN

The 11S globulin of seed storage protein of Amaranthus hypochondriacus, termed amarantin, was isolated. This fraction was evaluated for its purity by chromatographic techniques and ultracentrifugation. The 11S globulin was analyzed by sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) without and with prior reduction of disulfide bonds, and by nondenaturing-PAGE. It exhibited an electrophoretic behavior similar to that of 11S-like proteins in other materials. Its apparent relative molecular weight was estimated to be 389 kDa by gel filtration chromatography at low ionic strength. Ultracentrifugation of the freeze-dried extract gave a sedimentation coefficient of 11S.     

EVIDENCE FOR THE PHOSPHORYLATION AND GLYCOSYLATION OF THE AMARANTH 11S GLOBULIN (AMARANTHIN)

A series of 11S globulins isolated and purified from genetically different Amaranthus lines were found to be both glycosylated and phosphorylated to varying degrees, i.e., 4.0–7.8% and 0.030–0.058%, respectively. Carbohydrate was found to be N-linked to amino acids in the amaranth globulin and was composed of 28.0% xylose, 34.4% mannose 8.3% galactose and 29.3% glucose whereas phosphate was found to be O-linked with six residues per globulin molecule. Both co- or post-translational modifications were found to influence the hydrophilicity, surface charge characteristics and stability of the secondary conformation of the globulin. Glycosylation was shown to be important in the folding and assembly of the globulin, whereas phosphorylation was found to enhance the metal-binding capacity of the globulin.     

ISOLATION, PURIFICATION AND CHARACTERIZATION OF THE SEED STORAGE GLOBULIN AND ITS POLYMERIZED FORM FROM TRITICUM AESTIVUM

The salt-soluble globulin and its polymerized counterpart from wheat (Triticum aestivum) seed were isolated and purified to homogeneity employing both gel filtration and anion exchange chromatography. The two globulins were purified free of any purothionin (an oxidation-reduction protein) contamination. Some of the physico-chemical properties of purothionin are also reported. Both globulins were found to be oligomers composed of two polypeptide chains, i.e., 35,000 and 49,000 Da, with no apparent evidence of any covalent inter-chain disulfide linkages between these major subunits. The molecular weights for the globulin and its polymerized (i.e., polymerized via interchain disulfide bonds between various subunits of differing molecular weights, excluding any interchain disulfide bonds between the 35,000 and 49,000 Da subunits) counterpart were determined to be 474,000 and 567,000 Da, respectively, by gel chromatography. Surface charge profiles of fractions 2 and 3 were determined using electrophoretic isoelectric focusing, electrophoretic titration and zeta potential analysis and indicated pIs of 6.90 and 6.55, respectively. The nonpolymerized globulin was found to be more positively charged below its isoelectric point and less negatively charged above it than its polymerized counterpart. Microcalorimetric studies indicated that the two globulins had similar T_m values.     

ISOLATION AND CHARACTERIZATION OF TWO TRYPSIN-CHYMOTRYPSIN INHIBITORS FROM LENTIL SEEDS (LENS CULINARIS MEDIK.)1

The two major trypsin-chymotrypsin inhibitors of Lens culinaris Medik., LCI-1 and LCI-4, were purified to homogeneity from Italian red lentils by ammonium sulfate fractionation, gel and ion-exchange chromatography. At least two more trypsin-chymotrypsin inhibitors of minor importance were present. LCI-1 and LCI-4 inhibited human trypsin less (68–74%) but human chymotrypsin better (268–279%) than the respective bovine enzymes. The two inhibitors contained no carbohydrates, no methionine and no tryptophan and high contents ofcystine but no free sulfhydryl groups (seven and eight disulfide bridges for LCI-1 and LCI-4, respectively). In addition, LCI-4 contained no isoleucine. The isoelectric points were 5.35 and 7.70 and the average molecular weights 10,600 and 9,900 daltons for LCI-1 and LCI-4, respectively. Inhibitor extracts, as well as purified inhibitors in solution, were relatively stable against heating and treatment with human gastric juice, while soaking the whole seeds overnight and subsequent boiling for two hours totally destroyed inhibitor activity.     

ISOLATION AND CHARACTERIZATION OF MELANOIDINES FROM MALT AND MALT ROOTS

Preparative isolation of alcohol-soluble and water-soluble melanoidines from pale malt, caramel malt, coffee malt and malt roots was done. The distribution of melanoidines according to molecular weight and the spectral characterization of the separate fractions was studied by gel chromatography on Sephadex G-50. The melanoidines isolated from coffee malt have the largest molecular weights and those from pale malt the smallest. The alcohol-soluble melanoidines of malt are characterized by a greater diversity in spectra and absorbance maxima from 240 to 285 nm. The water-soluble melanoidines absorb in the region 265 to 283 nm.     

PURIFICATION AND PARTIAL CHARACTERIZATION OF A LECTIN FROM THE SEEDS OF DIOCLEA GUIANENSIS1

A lectin was purified from seeds of Dioclea guianensis by Sephadex G-50 affinity chromatography. Apparent homogeneity of the lectin was demonstrated by native polyacrylamide gel electrophoresis, chromatography on DEAE- and CM-Sepharose, and immunochemistry. The lectin showed a carbohydrate specificity for D-mannose (D-glucose)-binding, had a requirement for Ca^?2 and Mn^?2, contained no covalently bound carbohydrate and had an amino acid composition characterized by high content of aspartic acid, serine and threonine, and low levels of sulfur-containing amino acids. At pH 7.5 it exists as two species of molecular weight about 100 and 47 kD and in dissociating solvents three subunits of approximate size of 30, 18 and 12 kD were obtained. The lectin agglutinated erythocytes from rabbit and chicken but not from human, cow, sheep, goat or pig and was toxic to brine shrimp (Artemia salina) larvae. It was relatively heat-stable, retaining half of its original activity even after 90 min at 70°C.     

ISOLATION AND CHARACTERIZATION OF PECTINESTERASE FROM VALENCIA ORANGE1

Thermolabile (TL) and thermostable (TS) pectinesterases (PE) were extracted from the pulp of fresh Valencia oranges by enzyme hydrolysis using a native pH and high ionic strength buffer system. Each form was separated individually by CM-Sephadex C-50, Phenyl Sepharose CL-4B and CM-Bio-Gel A chromatography. TLPE and TSPE exist as multiple forms which were shown to differ in their stability and effects on cloud loss in single strength orange juice.     

苋菜籽和昆诺阿藜籽的营养和利用

介绍了欧洲人在食用谷物时产生的过敏反应的背景及针对谷物过敏症进行的无面筋食品原料资源—假谷物的开发情况,特别是苋菜籽和昆诺阿藜籽的营养价值和性质。     

甘薯糖蛋白的分离纯化及其性质研究

采用二乙基氨基52离子交换和葡聚糖凝胶G100柱层析法,从甘薯中分离纯化甘薯糖蛋白,并对其理化性质进行了研究.通过高效凝胶过滤色谱和SDS-聚丙烯酰胺凝胶电泳表明糖蛋白的纯度为97%;测得其分子量为58575u.采用DSC技术对甘薯水溶性糖蛋白热力学性质进行了研究,结果表明甘薯水溶性糖蛋白的热变性温度为106.67℃,而去糖基后的热变性温度为66.84℃,说明糖蛋白上的寡糖链有很好的稳定作用,具有增强糖蛋白抗变性功能.     

PURIFICATION AND PARTIAL CHARACTERIZATION OF A HEMAGGLUTININ FROM SEEDS OF JATROPHA CURCAS

An extract from Jatropha curcas seeds, purified by gel filtration on Sephadex G-75 and Sephacryl S-200, yielded an active hemagglutinin of high purity as assessed by electrophoresis and isoelectric focussing. The hemagglutinin had a molecular weight of around 660,000 and a pI value of 5.75. The molecule was composed of two different subunits of molecular weights 23,450 and 11,500. Amino acid analysis suggested that the molecule lacked 1/2 cystine but contained a high proportion of acidic and basic amino acids. Agglutination of trypsinized erythrocytes, groups A, B and O, took place over the range pH 4–10, and was prevented by D- galactose, D- galactosamine and N- acetyl -D- galactosamine. The hemagglutinin has only a weak binding capacity for D- galactose. Its activity was stable up to 60°C; at 80°C activity was lost in 50 min.     

白底辐肛参酸性黏多糖的分离及特性研究

以K2CO3和木瓜蛋白酶从白底辐肛参中提取粗多糖，再以H2O2除色素，乙酸钾蛋白，柱层析后得到精制的酸性黏多糖，琼脂糖凝胶电泳表明其为单一成分。凝胶渗透色谱法测得分子量为71098u，多糖组成中硫酸基、葡萄糖醛酸、氨基半乳糖、岩藻糖含量分别为30．6％、15．46％、17．75％、13．56％。     

RHEOLOGICAL PROPERTIES OF HEATED CORN STARCH + SOYBEAN 7S AND 11S GLOBULIN DISPERSIONS

At 10% solids content, magnitudes of G' and G" of soybean 7S dispersion were substantially lower than those of corn starch dispersion, while those of soybean 11S dispersion were much higher than those of starch. Profiles of G' at 30 Hz as a function of starch concentration of starch + 7S and starch + 11S gels were asymmetrical reflecting phase separation due to thermodynamic incompatibility. However, the starch concentration corresponding to the critical point below which no phase separation occurs for the starch + 7S dispersion was about 7% and for the starch + 11S dispersion it was about 3%. At equal starch fractions, values of G' at 30 rad s^-1 of corn starch + 7S dispersions were nearly equal to those of only corn starch. In contrast, at starch concentrations between 6–8%, G' values of the corn starch + 11S dispersions were much higher than those of only starch and a minimum value occurred at a starch concentration of about 5%. Based on frequency dependence of G' values, heated corn starch + 7S dispersions may be classified as weak gels, while heated corn starch + 11S dispersions may be classified as true gels.