Molecular changes of phenolic-protein interactions in isolated proteins from flaxseed and soybean using Native-PAGE, SDS-PAGE, RP-HPLC, and ESI-MS analysis.

The effects of protein-phenolic interactions on the molecular characteristics of soybean and flaxseed proteins were investigated. Proteins were isolated from soybean and flaxseed using isoelectric precipitation, followed by extraction of free and bound phenolics. The effects of elimination of the phenolic compounds on molecular characteristics of the protein isolates were studied using reversed phase-high performance liquid chromatography (RP-HPLC), Native and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE) and electron spray ionization-mass spectrometry (ESI-MS).

Occurrence, types, properties and interactions of phenolic compounds with other food constituents in oil-bearing plants.

Phenolic phytochemicals have become of interest due to their therapeutic potential, particularly with regards to their anti-cancer, anti-inflammatory, hypolipidemic, and hypoglycemic properties. An evolving area of research involving phenolics in foods and their products pertains to the functional, biological, and nutritional consequences resulting from the binding between certain phenolic compounds and the macronutrient and micronutrient constituents of foods. The goal of this review is to provide a summary of studies investigating endogenous phenolic interactions with major components in food systems, including carbohydrates, proteins, lipids, minerals and vitamins, with a focus on the phenolic compounds and nutrients in oil-bearing plants.

A review of phenolic compounds in oil-bearing plants: Distribution, identification and occurrence of phenolic compounds.

Over the last two decades, separation, identification and measurement of the total and individual content of phenolic compounds has been widely investigated. Recently, the presence of a wide range of phenolic compounds in oil-bearing plants has been shown to contribute to their therapeutic properties, including anti-cancer, anti-viral, anti-oxidant, hypoglycemic, hypo-lipidemic, and anti-inflammatory activities. Phenolics in oil-bearing plants are now recognized as important minor food components due to several organoleptic and health properties, and they are used as food or sources of food ingredients.

Interactions of caseins with phenolic acids found in chocolate.

To investigate the interactions between caseins and phenolic acids, such as the ones present in chocolate, casein was incubated with protocatechuic acid or p-coumaric acid at 55°C. In addition, casein was isolated from chocolate and the phenolic compounds within these caseins were quantified. Electrophoresis results revealed that casein-phenolic interactions were induced by incubation; minor aggregation of casein subunits was observed after incubation of casein with protocatechuic acid.

Effect of phenolic compound removal on rheological, thermal and physico-chemical properties of soybean and flaxseed proteins.

This study aimed to investigate the effect of removal of phenolics on physico-chemical properties of protein isolates obtained from flaxseed and soybean. Proteins were isolated (I) from full-fat (F) and defatted (D) soybean (s) and flaxseed (f) using isoelectric precipitation. Free and bound phenolics were removed from the protein isolates.

Potato protein isolates: recovery and characterization of their properties.

An imitation of industrial potato fruit juice (PFJ) was prepared, using Canadian variety of potatoes, and was characterized of being composed of 22.9% patatin, 53.3% protease inhibitors, and 23.

Distribution, antioxidant and characterisation of phenolic compounds in soybeans, flaxseed and olives.

The distribution of free and bound phenolic compounds present in soybean, flaxseed and olive were investigated. The phenolic compounds were fractionated on the basis on their solubility characteristics in water, alcohol, dilute base and dilute acid. Reversed phase high pressure liquid chromatography (RP-HPLC) and mass spectrometry (MS) were used for identification of individual components of phenolic compounds.

Mutation studies in the active site of β-glycosidase from Pyrococcus furiosus DSM 3638.

Sequence alignments and homology modeling of Pyrococcus furiosus thermostable glycosidase (PFTG) showed that the residue 150 is conserved as tryptophan in β-glycosidase and in other related enzymes such as β- mannosidase and β-galactosidase. To elucidate the relationship between the substrate size and geometric shape of the catalytic site of thermophilic β-glycosidase and category of PFTG, the Q77, Q150 and D206 located at the interface of the dimer were replaced with Trp and Asn. Also, to confirm the role of active sites of PFTG, the Q77R/Q150W double mutant was created through subcloning.

Overexpression and characterization of a novel transgalactosylic and hydrolytic β-galactosidase from a human isolate Bifidobacterium breve B24.

After the complete gene of a β-galactosidase from human isolate Bifidobacterium breve B24 was isolated by PCR and overexpressed in E. coli, the recombinant β-galactosidase was purified to homogeneity and characterized for the glycoside transferase (GT) and glycoside hydrolase (GH) activities on lactose. One complete ORF encoding 691 amino acids (2,076 bp) was the structural gene, LacA (galA) of the β-gal gene.

Expression and characterization of an extremely thermostable β-glycosidase (mannosidase) from the hyperthermophilic archaeon Pyrococcus furiosus DSM3638.

Genomic analysis of the hyperthermophilic archaeon Pyrococcus furiosus revealed the presence of an open reading frame (ORF PF0356) similar to the enzymes in glycoside hydrolase family 1. This β-glycosidase, designated PFTG (P. furiosus thermostable glycosidase), was cloned and expressed in Escherichia coli.

Optimisation and characterisation of various extraction conditions of phenolic compounds and antioxidant activity in olive seeds.

This study was conducted to optimise the extraction conditions of phenolic compounds to evaluate antioxidant extraction parameters and to identify the major free and bound phenolic compounds in olive seeds. The results obtained using methanol as an extraction solvent for olive seeds indicated that the optimised total phenolic content and antioxidant activity were obtained at an extraction time of 12 h, an extraction temperature of 70°C and an extraction cycle of three stages. The correlation coefficient between total phenolic compounds and antioxidant activities was positive (R² = 0.

Effect of limited solid-state glycation on the conformation of lysozyme by ESI-MSMS peptide mapping and molecular modeling.

Although protein glycation has been implicated in the alteration of protein functionality, both in vivo (in biological systems) and in vitro (in food systems), the effect of the protein-bound glycan moiety on the structure/conformation of proteins that result in the modification of functionality is not clear. In this article, we report a study of the conformational changes of glycated lysozyme using LC-ESI-MSMS peptide mapping, and molecular modeling. A comparison of the RP-HPLC of the tryptic digests of unglycated and glycated lysozyme showed markedly different chromatographic profiles.

Charge state distribution and hydrogen/deuterium exchange of alpha-lactalbumin and beta-lactoglobulin preparations by electrospray ionization mass spectrometry.

Charge state distribution (CSD) and hydrogen/deuterium (H/D) exchange of preparations of alpha-lactalbumin (alpha-Lac) and beta-lactoglobulin (beta-Lg) were investigated using electrospray ionization mass spectrometry (ESI-MS). Storage of alpha-Lac at pH 3 resulted in substantial changes in its CSD, with the emergence of new ion species and shifts toward higher charge state, indicating less stable conformation. ESI spectra of alpha-Lac kept at pH 5.

Protein-lipid interactions in food systems: a review.

Proteins and lipids, both individually or as complexes, play important functional roles in foods. Since the 1970s food scientists have devoted attention to the nature of these interactions and particularly to their effects on functional characteristics of protein-based foods. Previously, most of the published work was devoted to the biochemical aspects of protein-lipid interactions in biological systems.