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Biomedical subjects

E E Braudo

Publications and source records attributed to E E Braudo.

At least 19 recordsLinked to original sources
PubMed2006

Adsorption at the air-water interface and emulsification properties of grain legume protein derivatives from pea and broad bean.

Functional properties of native and modified (through induced autolysis) pea (Pisum sativum L.) and broad bean (Vicia faba L.) protein derivatives are studied. In specific, protein solubility and behavior at the air-water interface through surface pressure measurements are investigated. Furthermore the ability of the protein products to act as emulsifying agents and to stabilize emulsions is studied through oil droplet size distribution measurements and by the protein adsorbed at the oil-water interface. The data reveal that the ability of the proteins to act as surfactants and build up a rigid film around the oil droplets, mainly depends on their suitable molecular configuration and structure. Hydrolysis did not promote the functionality of the legume proteins. Broad bean exhibited better functionality than pea, before and after hydrolysis. Some comparisons were also made with lupin (Lupinus albus L.) protein isolate.

Adsorption↗
PubMed2006

Comparative effects of limited tryptic hydrolysis on physicochemical and structural features of seed 11S globulins.

The effect of the limited proteolysis by trypsin on selected seed storage 11S globulins (broad bean and pea legumins, glycinin and helianthinin) was studied by high-sensitive differential scanning calorimetry, fluorescence spectroscopy and analysis of proteolysis kinetics. Different behaviour of glycinin and helianthinin, on one hand, and broad bean and pea legumins, on the other, were observed: in the first group changes in the physicochemical characteristics of the proteins due to their limited proteolysis are more pronounced in comparison with the second one, in relation with the extent of primary structure modifications. The differences observed have been evaluated in relation with the amino acid sequence features of the four 11S globulin studied and agree with the literature data concerning the protein structural changes in the course of the limited proteolysis.

2S Albumins, Plant↗
PubMed2001

Comparative studies on thermodynamic characteristics of pea legumin and legumin-T thermal denaturation.

Characteristics of thermal denaturation of pea legumin and a product of its limited proteolysis with trypsin - legumin-T, in a wide range of NaCl concentrations have bean measured by means of differential scanning microcalorimetry. By the increase of NaCl concentration, the number of cooperative units (domains) increases from 1 per one polypeptide chain to 2 for legumin and 1.8 for legumin-T. Deconvolution of denaturation peaks have revealed up to three peaks, which were ascribed to the dissociation of protein macromolecules to subunits and the unfolding of alpha- and beta-polypeptide chains. The analysis of experimental data based on some assumptions showed that the splitting of C-termini of alpha-chains, which are not constituents of cooperative domains, in the course of limited trypsinolysis results in destabilization of the quaternary structure of legumin and loosening of alpha-chains, as well as decrease of the temperatures of their maximum stability.

Calorimetry↗
PubMed2001

Limited tryptic hydrolysis of pea legumin: molecular mass and conformational stability of legumin-T.

The investigation of hydrodynamic and thermodynamic properties and the determination of the molecular mass of legumin-T, the product of limited tryptic hydrolysis of the 11-S-globulin from pea seeds, was carried out to ascertain the structural relationship to globulin-T's from other legumin-like proteins. The obtained legumin-T preparation has a molecular mass M(W)=260+/-10 kDa and M(S,D)=270+/-20 kDa. The secondary structure of legumin-T is characterised by a high percentage of beta-sheet conformation, comparable to that of native legumin and a reduced percentage of helical conformation. The conformational stability of legumin-T evaluated by equilibrium unfolding in the presence of guanidinium chloride was only slightly reduced in comparison to the native legumin, whereas the calorimetrically determined denaturation enthalpy and Gibbs energy of denaturation were found to be increased for legumin-T. These physicochemical properties are very similar to those of faba bean legumin-T.

Calorimetry↗
PubMed2001

Plant protein interactions with polysaccharides and their influence on legume protein functionality. A review.

Associative interactions between proteins and polysaccharides, both coulombic and non-coulombic, lead to the formation of interpolymer complexes. Complex formation with charged polysaccharides, either anionic or cationic, imparts solubility to seed globulins in the vicinity of their isoelectric points. This has been shown for the complexes "sunflower 11 S globulin (helianthinin)--sodium alginate" and "faba bean legumin (or the product of its limited proteolysis with trypsin--legumin-T)--chitosan". Hysteresis effects allow to control the solubility of seed globulins in weakly acid or weakly basic media. Formation of soluble complexes of faba bean legumin or legumin-T with chitosan substantially increases the emulsion stability of the both proteins.

Chitin↗
PubMed2001

Alternative approaches to the manufacture of plant protein products from grain legumes.

A biotechnological method for the modification of grain legume meals (pea, faba bean) is proposed. The essence of this method is the inducing of biochemical processes, which occur at the germination, through the treatment of a meal with an acid protease. Modified meals can replace soybean protein isolate as meat extenders. In particular, the modification of pea meal improves the colour of combined meat products and eliminates their beany off-flavour. The concentration of six-carbon aldehydes in combined sausages is reduced after the modification of pea meal.

Animals↗
PubMed2001

[Thermodynamic approach to the selection of polyuronide sequestrants for the protection of the human body from toxic metal ions. Interactions of polyuronides with strontium and calcium ions].

Selectivity of polyuronide sequestrants (pectate, alginates of various uronide composition) in respect to Sr2+ and Ca2+ ions has been evaluated in terms of thermodynamic affinity. It is suggested that there is no point in the use of pectate as a Sr(2+)-binding agent because at initial stages of reaction it reveals higher affinity to Ca2+ ions in comparison to Sr2+ ions. Contrary to pectate, alginates under similar conditions have higher affinity to Sr2+ ions. It is shown that these ions are bound only by blocks of L-guluronic acid residues in alginate macromolecules. The results obtained lend support to the advisability of the use of alginate preparations with the high content of L-guluronic acid residues for the excretion of Sr2+ ions from human body.

Alginates↗
PubMed2001

[Thermodynamic approach to the selection of polyuronide sequestrants for protection of the human body from toxic metal ions. Interactions of polyuronides with lead ions].

Binding isotherms of Pb2+ ions with potassium pectate and potassium alginate with relatively low content of blocks of L-guluronic residues (20%) have been determined. Interactions of Pb2+ ions with polyuronides studied is cooperative. Maximum values of binding constants are an order of magnitude higher than previously determined ones for Ca2+ and Sr2+ ions. Along with ion-coordination ("stoichiometric") interactions, alginate is typified by so-called extra-stoichiometric binding of Pb2+ ions, which presumably proceeds by a coprecipitation mechanism. Limitations of the thermodynamic approach to the selection of sequestrants for human body protection from toxic metal ions are discussed.

Alginates↗
PubMed2000

Interactions of flavor compounds with pectic substances.

Investigation has been conducted using equilibrium dialysis on the sorption of flavor compounds (FC) in solutions of low- and high-esterified pectinates (LEP and HEP, respectively). The compounds include 2-acetyl pyridine, 2,3-diethyl pyrazine, 2-acetyl thiophene and some normal 2-ketones. A method of direct gas chromatographic analysis has been developed for the determination of the FC in aqueous solutions at concentrations as low as 10(-3)% v/v. Additional information was obtained by the analysis of circular dichroism (CD) and apparent molar heat capacity. The results indicate: (1) In LEP solutions, sorption of normal aliphatic 2-ketones with chain length greater than C6 presumably proceeds via van der Waals interactions between alkyl groups of the 2-ketone and hydrophobic regions of the pectinate. The sorption increases with increased alkyl chain length. The Gibbs energy of the methylene group transferring from the solvent to the LEP solution is found to be 1.8 kJ/mol for 2-ketones at C7-C9. (2) In acidic media, binding of heterocyclic FC with pectinates mostly proceeds via hydrogen bonding involving the hydrogen atoms in undissociated carboxyl groups in the pectinate macromolecules. It can also be affected by the self-association of the pectinate macromolecules, depending on pH and pectinate concentration. (3) Under neutral conditions, the presence of Mg2+, Ca2 and Zn2+ ions or the formation of the calcium-pectinate gel network has little effect on the sorption of 2-ketones with the LEP. However, in acidic media, metal ions inhibit the sorption of FC through hydrogen bonding. The sorption of 2-octanone in acidic media depends extremely on Ca++ concentration by the correlationship with changes in the structure of LEP solutions in terms of apparent molar heat capacity.

Algorithms↗
PubMed1996

Thermodynamic approach to the selection of polyuronide sequestrants for preventive and medicinal nutrition.

An approach to the analysis of isotherms of cooperative binding is developed that allows to calculate approximately affinity profiles, i.e. dependencies of binding constants on binding densities. The comparison of the affinity profiles of the interactions of Ca2+ and Sr2+ ions with sodium pectate as well as sodium alginates with the different content of the blocks of alpha-L-guluronic acid residues (GG-blocks) and blocks of mixed composition showed that (1) pectate has higher affinity to both ions as compared with alginates; (2) the affinity of pectate to Ca2+ ions is comparable to its affinity to Sr2+ ions but in the case of Ca2+ ions the maximum of the affinity profile falls on the substantially lesser value of the binding density in comparison to Sr2+ ions that seems to be unfavorable from the standpoint of the use of this polyuronide in preventive or medicinal nutrition; (3) the affinity of both alginates to Sr2+ ions at relatively low binding densities exceeds their affinity to Ca2+ ions; (4) the affinity of alginates to Sr2+ ions increases with the increase in the content of GG-blocks, whereas the affinity to Ca2+ ions practically does not depend on the composition of the alginate; (5) the maximum binding density of Sr2+ ions to the alginates approximately corresponds to the content of GG-blocks. These results corroborate the practice of the use of alginates rich in residues of alpha-L-guluronic acid for the removal of radioactive strontium from the digestive tract. The binding constants of Pb2+ ions to pectate over a wide range of binding densities are more than an order of magnitude greater than those of alkali-earth metal ions.

Alginates↗
PubMed1985

Starch as a functional component of food systems.

Starch and other carbohydrates of D-glucose series bind sodium ions but don't bind calcium ones. The affinity of beta-glucosides to sodium ions is much stronger than the affinity of D-glucose and of alpha-glucosides. Some other interrelations between the components of starch-containing food systems are briefly discussed.

Carbohydrate Conformation↗
PubMed1979

[Rheological properties of a calcium alginate-potato starch hydrolysate-water system].

The rheological properties of liquid solutions and gels of sodium alginate, calcium gluconate and gelling maltodextrin were investigated and compared with the behaviour of pastes and gels of non-degraded potato starch. The dependence of the rheological properties upon the calcium gluconate concentration is extreme. A marked increase in the viscosity of the liquid solutions and maximal values for the hardness and the breaking strength of the gels are obtained at a calcium gluconate/sodium alginate ratio of 0.3. As to breaking strength, elasticity and hardness, the maltodextrin-based gels are many times inferior to the potato starch-based gels. The breaking strength, hardness and elasticity of maltodextrin gels are increased by the addition of sodium alginate and calcium gluconate, which increases their effectiveness when used in foods.

Alginates↗
PubMed1976

[Artificial macaroni. 2. Biological value of synthetic macaroni].

The authors determined (in vitro) the amino-acid composition and the enzymatic cleavage of protein and starch as well as (in vivo) the biological value of synthetic macaroni produced on the basis of casein, soybean protein and cotton-seed protein. The products based on casein and soybean protein have a great biological value. Cotton-seed protein has a toxic effect. The biological value of synthetic macaroni is mainly determined by the composition of the initial mixture. The processes of production and culinary processing exert no essential effects on protein content, amino-acid composition of the protein and enzymatic cleavage.

Amino Acids↗
PubMed1975

[Effect of acid polysaccharides on properties of pancreatic proteases].

The use of acid polysaccharides (sodium alginate, pectin, carrageenan, etc.) as gel-forming agents in the manufacture of artificial foods excites the interest in the study of their effects on the enzymes of the gastrointestinal tract. In this connection, the authors investigated the action of various acid polysaccharides on the kinetics of the hydrolysis of low-molecular substrates catalyzed by pancreatic proteinases. It was shown that the intereactions between acid polysaccharides and enzymes produce effects which can be fully explained by changes in the apparent ionization constants of the ionogenic groups which participate in the catalytic reaction. The extent of the effects observed in presumably determined by the strength of the electrostatic potential which is generated by polyanions.

Alginates↗
PubMed1975

[Physicochemical aspects of synthetic food production].

The authors discuss the general approach to the problem of the protein architecture and the working of proteins to synthetic foods. They present the main results from relevant studies on the compatibility and interactions of proteins and polysaccharides in aqueous media and deal with possibilities of influencing the structure formation and the physical properties of gels of given composition.

Alginates↗