Sooyoun Seo - Academia.edu (original) (raw)

Papers by Sooyoun Seo

Research paper thumbnail of Interactions of caseins with phenolic acids found in chocolate

Food Research International, Aug 1, 2015

To investigate the interactions between caseins and phenolic acids, such as the ones present in c... more 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. Minor aggregation of casein isolated from milk chocolate was also observed. In vitro hydrolysis of casein control, casein-protocatechuic acid, casein-pcoumaric acid, caseins isolated from milk chocolate and white chocolate using trypsin showed degree of hydrolysis of 19.3, 18.6, 17.7, 10.4 and 17.8% respectively. The presence of protocatechuic acid and p-coumaric acid in the model system and the presence of phenolic compounds in milk chocolate, in addition to the structural changes occurring during processing, affected the peptide profiles of casein hydrolysates.

Research paper thumbnail of Enzymatic Synthesis of Galactosylated Serine/Threonine Derivatives by β-Galactosidase from Escherichia coli

International Journal of Molecular Sciences, 2015

The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase... more The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase from Escherichia coli as biocatalyst. Using ortho-nitrophenyl-β-D-galactoside as donor, the highest bioconversion yield of transgalactosylated N-carboxy benzyl L-serine benzyl ester (23.2%) was achieved in heptane:buffer medium (70:30), whereas with the lactose, the highest bioconversion yield (3.94%) was obtained in the buffer reaction system. The structures of most abundant galactosylated serine products were characterized by MS/MS. The molecular docking simulation revealed that the binding of serine/threonine derivatives to the enzyme's active site was stronger (−4.6~−7.9 kcal/mol) than that of the natural acceptor, glucose, and mainly occurred through interactions with aromatic residues. For N-tert-butoxycarbonyl serine methyl ester (6.8%) and N-carboxybenzyl serine benzyl ester (3.4%), their binding affinities and the distances between their hydroxyl side chain and the 1′-OH group of galactose moiety were in good accordance with the quantified bioconversion yields. Despite its lower predicted bioconversion yield, the high experimental bioconversion yield obtained with N-carboxybenzyl serine methyl ester (23.2%) demonstrated the importance of the thermodynamically-driven nature of the transgalactosylation reaction.

Research paper thumbnail of Characterization of glycated lysozyme with galactose, galactooligosaccharides and galactan: Effect of glycation on structural and functional properties of conjugates

LWT - Food Science and Technology, 2013

Glycated lysozyme (LZM) with galactose, galactooligosaccharides (GOSs) and galactan, through the ... more Glycated lysozyme (LZM) with galactose, galactooligosaccharides (GOSs) and galactan, through the Maillard reaction, were produced and characterized structurally and functionally. The extent of glycation of LZM was evaluated by the measurement of the blocked lysine and the formed furosine. The results indicated a high initial reactivity of galactose as compared to GOSs and galactan. In the presence of GOSs, the oxidative and cross-linking side reactions competed with the initial formation of Amadori product. The longer chain carbohydrate galactan exhibited the lowest initial rate of glycation with no significant cross-linking side reaction. Electrospray ionization mass spectrometry revealed the formation of glycated LZM containing up to eight galactose moieties; while only mono-to tetra-glycated LZM with GOSs were detected. 2e3 mol of galactan were conjugated to 1 mol of LZM. Galactan:LZM conjugates exhibited higher solubility, thermal stability and emulsion stability as compared to the unmodified LZM and LZM:galactose conjugates. LZM:GOS conjugates demonstrated the most improvement in the emulsion stability than the other conjugates. Furthermore, the glycation of LZM with galactose/GOSs/galactan decreased its immunoreactivity.

Research paper thumbnail of Investigation of the Use of Maillard Reaction Inhibitors for the Production of Patatin–Carbohydrate Conjugates

Journal of Agricultural and Food Chemistry, 2014

Research paper thumbnail of Preparation of Potato Galactooligosaccharide and Galactan Derivatives by Maillard-type Glycation With Lysozyme

Journal of Biotechnology, 2010

Research paper thumbnail of Allergenicity of Potato Proteins and of Their Conjugates with Galactose, Galactooligosaccharides, and Galactan in Native, Heated, and Digested Forms

Journal of Agricultural and Food Chemistry, 2014

The effect of glycation of potato proteins on their immunoreactivity was studied by using a pool ... more The effect of glycation of potato proteins on their immunoreactivity was studied by using a pool of human sera with specific IgE to potato proteins. Patatin conjugates were more immunoreactive than protease inhibitors ones. To better understand this behavior, the changes in patatin structure upon glycation and heat treatment were investigated. Patatin demonstrated an increase in total immunoreactivity when glycated with galactose and galactooligosaccharides. However, galactan conjugation to patatin resulted in a decrease in immunoreactivity by restricting IgE's access to the epitopes. Although the heat treatment resulted in a decrease in patatin's immunoreactivity through aggregation, it was less effective when patatin conjugates were used due to the decrease in aggregation and the secondary structural changes. Upon digestion, native patatin exhibited the largest decrease in immunoreactivity resulting from the disruption of both conformational and sequential epitopes. Patatin conjugates were less digested and had higher IgE-immunoreactivity as compared to the digested patatin.

Research paper thumbnail of Production and characterisation of potato patatin–galactose, galactooligosaccharides, and galactan conjugates of great potential as functional ingredients

Food Chemistry, 2014

Potato proteins are of high interest because of their high nutritional quality and multiple healt... more Potato proteins are of high interest because of their high nutritional quality and multiple health benefits, but they are currently undervalued due to their limited solubility and stability. Glycated patatin (PTT) with galactose, galactooligosaccharides (GOSs) and galactan were produced through the Maillard reaction and characterised structurally and functionally. Fourier-transform infrared and fluorescence spectroscopy data revealed important changes in total secondary structures through glycation with GOSs (61.2%) and galactan (36.7%) and also significant tertiary structural changes leading to an exposure of tryptophan residues. These structural changes led to more heat stable forms of PTT with a higher unfolding temperature (70-90 °C) than the unmodified protein (50-70 °C) and with higher antioxidant activity. PTT:galactose conjugates exhibited similar thermal stability and pH-structural behaviour to native PTT. However, the high level of galactose conjugation to PTT and increased exposure of hydrophobic residues led to a significant increase in its emulsifying stability at pH 3.

Research paper thumbnail of Glycation of lysozyme with galactose, galactooligosaccharides and potato galactan through the Maillard reaction and optimization of the production of prebiotic glycoproteins

Process Biochemistry, 2012

The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and pot... more The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and potato galactan through the Maillard reaction, was investigated. The percent blocked lysine, estimated from the furosine content, reached a maximum value of 11.2% for LZM:galactan conjugates after 1 day incubation at a a w of 0.65. A maximum percent blocked lysine of 7.0 and 13.5% were obtained for LZM:galactose/GOS conjugates at a lower a w of 0.45 after 3 and 7 days, respectively. However, the low percent blocked lysine and the high protein aggregation index of LZM:galactose/GOS conjugates at a w 0.79 and 0.65 revealed the prevalence of the degradation of the Amadori compounds and the protein cross-linking. Mass spectrometry of LZM conjugates revealed the formation of different glycoforms. Glycated LZMs containing up to seven galactose moieties were formed; while only mono-and diglycated LZMs with GOSs were detected. 2-3 mol of galactan were conjugated to 1 mol of LZM. Response surface methodology, based on a 5-level and 3-factor central composite design, revealed that molar ratio and temperature were the most significant variables for the glycation of LZM with GOSs. The optimal conditions leading to a high percent blocked lysine (16.11%) with a low protein aggregation index (0.11) were identified: temperature of 49.5 • C, LZM:GOS molar ratio of 1:9 and a w of 0.65. To the best of our knowledge, this is the first study on the optimization of LZM glycation with GOSs.

Research paper thumbnail of Article Enzymatic Synthesis of Galactosylated Serine/Threonine Derivatives by β-Galactosidase from Escherichia coli

Abstract: The transgalactosylations of serine/threonine derivatives were investigated using β-gal... more Abstract: The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase from Escherichia coli as biocatalyst. Using ortho-nitrophenyl-β-D-galactoside as donor, the highest bioconversion yield of transgalactosylated N-carboxy benzyl L-serine benzyl ester (23.2%) was achieved in heptane:buffer medium (70:30), whereas with the lactose, the highest bioconversion yield (3.94%) was obtained in the buffer reaction system. The structures of most abundant galactosylated serine products were characterized by MS/MS. The molecular docking simulation revealed that the binding of serine/threonine derivatives to the enzyme’s active site was stronger (−4.6~−7.9 kcal/mol) than that of the natural acceptor, glucose, and mainly occurred through interactions with aromatic residues. For N-tert-butoxycarbonyl serine methyl ester (6.8%) and N-carboxybenzyl serine benzyl ester (3.4%), their binding affinities and the distances between their hydroxyl side chain and the 1′...

Research paper thumbnail of Biotransformation of sucrose rich Maple syrups into fructooligosaccharides, oligolevans and levans using levansucrase biocatalyst: Bioprocess optimization and prebiotic activity assessment

Research paper thumbnail of Interactions of caseins with phenolic acids found in chocolate

Food Research International, 2015

To investigate the interactions between caseins and phenolic acids, such as the ones present in c... more 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. Minor aggregation of casein isolated from milk chocolate was also observed. In vitro hydrolysis of casein control, casein-protocatechuic acid, casein-p-coumaric acid, caseins isolated from milk chocolate and white chocolate using trypsin showed degree of hydrolysis of 19.3, 18.6, 17.7, 10.4 and 17.8% respectively. The presence of protocatechuic acid and p-coumaric acid in the model system and the presence of phenolic compounds in milk chocolate, in addition to the structural changes occurring during processing, affected the peptide profiles of casein hydrolysates.

Research paper thumbnail of Bacillus amyloliquefaciens levansucrase-catalyzed the synthesis of fructooligosaccharides, oligolevan and levan in maple syrup-based reaction systems

Carbohydrate Polymers, 2015

Maple syrups with selected degree Brix (°Bx) (15, 30, 60) were investigated as reaction systems f... more Maple syrups with selected degree Brix (°Bx) (15, 30, 60) were investigated as reaction systems for levansucrase from Bacillus amyloliquefaciens. The enzymatic conversion of sucrose present in the maple syrup and the production of the transfructosylation products were assessed over a time course of 48h. At 30°C, the use of maple syrup 30°Bx led to the highest levansucrase activity (427.53μmol/mg protein/min), while maple syrup 66°Bx led to the highest converted sucrose concentration (1.53M). In maple syrup 30°Bx, oligolevans (10<DP≤30) were synthesized as major products (>80%). In maple syrup 66°Bx, the most abundant products were oligolevans at 30°C and levans (DP≥30) at 8°C. The acceptor specificity study revealed the ability of B. amyloliquefaciens levansucrase to synthesize a variety of hetero-fructooligosaccharides (FOSs) in maple syrups 15°Bx and 30°Bx enriched with various disaccharides, with lactose being the preferred fructosyl acceptor. The current study is the first to investigate maple-syrup-based reaction systems for the synthesis of FOSs/oligolevans/levans.

Research paper thumbnail of Interactions of caseins with phenolic acids found in chocolate

Food Research International, Aug 1, 2015

To investigate the interactions between caseins and phenolic acids, such as the ones present in c... more 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. Minor aggregation of casein isolated from milk chocolate was also observed. In vitro hydrolysis of casein control, casein-protocatechuic acid, casein-pcoumaric acid, caseins isolated from milk chocolate and white chocolate using trypsin showed degree of hydrolysis of 19.3, 18.6, 17.7, 10.4 and 17.8% respectively. The presence of protocatechuic acid and p-coumaric acid in the model system and the presence of phenolic compounds in milk chocolate, in addition to the structural changes occurring during processing, affected the peptide profiles of casein hydrolysates.

Research paper thumbnail of Enzymatic Synthesis of Galactosylated Serine/Threonine Derivatives by β-Galactosidase from Escherichia coli

International Journal of Molecular Sciences, 2015

The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase... more The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase from Escherichia coli as biocatalyst. Using ortho-nitrophenyl-β-D-galactoside as donor, the highest bioconversion yield of transgalactosylated N-carboxy benzyl L-serine benzyl ester (23.2%) was achieved in heptane:buffer medium (70:30), whereas with the lactose, the highest bioconversion yield (3.94%) was obtained in the buffer reaction system. The structures of most abundant galactosylated serine products were characterized by MS/MS. The molecular docking simulation revealed that the binding of serine/threonine derivatives to the enzyme's active site was stronger (−4.6~−7.9 kcal/mol) than that of the natural acceptor, glucose, and mainly occurred through interactions with aromatic residues. For N-tert-butoxycarbonyl serine methyl ester (6.8%) and N-carboxybenzyl serine benzyl ester (3.4%), their binding affinities and the distances between their hydroxyl side chain and the 1′-OH group of galactose moiety were in good accordance with the quantified bioconversion yields. Despite its lower predicted bioconversion yield, the high experimental bioconversion yield obtained with N-carboxybenzyl serine methyl ester (23.2%) demonstrated the importance of the thermodynamically-driven nature of the transgalactosylation reaction.

Research paper thumbnail of Characterization of glycated lysozyme with galactose, galactooligosaccharides and galactan: Effect of glycation on structural and functional properties of conjugates

LWT - Food Science and Technology, 2013

Glycated lysozyme (LZM) with galactose, galactooligosaccharides (GOSs) and galactan, through the ... more Glycated lysozyme (LZM) with galactose, galactooligosaccharides (GOSs) and galactan, through the Maillard reaction, were produced and characterized structurally and functionally. The extent of glycation of LZM was evaluated by the measurement of the blocked lysine and the formed furosine. The results indicated a high initial reactivity of galactose as compared to GOSs and galactan. In the presence of GOSs, the oxidative and cross-linking side reactions competed with the initial formation of Amadori product. The longer chain carbohydrate galactan exhibited the lowest initial rate of glycation with no significant cross-linking side reaction. Electrospray ionization mass spectrometry revealed the formation of glycated LZM containing up to eight galactose moieties; while only mono-to tetra-glycated LZM with GOSs were detected. 2e3 mol of galactan were conjugated to 1 mol of LZM. Galactan:LZM conjugates exhibited higher solubility, thermal stability and emulsion stability as compared to the unmodified LZM and LZM:galactose conjugates. LZM:GOS conjugates demonstrated the most improvement in the emulsion stability than the other conjugates. Furthermore, the glycation of LZM with galactose/GOSs/galactan decreased its immunoreactivity.

Research paper thumbnail of Investigation of the Use of Maillard Reaction Inhibitors for the Production of Patatin–Carbohydrate Conjugates

Journal of Agricultural and Food Chemistry, 2014

Research paper thumbnail of Preparation of Potato Galactooligosaccharide and Galactan Derivatives by Maillard-type Glycation With Lysozyme

Journal of Biotechnology, 2010

Research paper thumbnail of Allergenicity of Potato Proteins and of Their Conjugates with Galactose, Galactooligosaccharides, and Galactan in Native, Heated, and Digested Forms

Journal of Agricultural and Food Chemistry, 2014

The effect of glycation of potato proteins on their immunoreactivity was studied by using a pool ... more The effect of glycation of potato proteins on their immunoreactivity was studied by using a pool of human sera with specific IgE to potato proteins. Patatin conjugates were more immunoreactive than protease inhibitors ones. To better understand this behavior, the changes in patatin structure upon glycation and heat treatment were investigated. Patatin demonstrated an increase in total immunoreactivity when glycated with galactose and galactooligosaccharides. However, galactan conjugation to patatin resulted in a decrease in immunoreactivity by restricting IgE's access to the epitopes. Although the heat treatment resulted in a decrease in patatin's immunoreactivity through aggregation, it was less effective when patatin conjugates were used due to the decrease in aggregation and the secondary structural changes. Upon digestion, native patatin exhibited the largest decrease in immunoreactivity resulting from the disruption of both conformational and sequential epitopes. Patatin conjugates were less digested and had higher IgE-immunoreactivity as compared to the digested patatin.

Research paper thumbnail of Production and characterisation of potato patatin–galactose, galactooligosaccharides, and galactan conjugates of great potential as functional ingredients

Food Chemistry, 2014

Potato proteins are of high interest because of their high nutritional quality and multiple healt... more Potato proteins are of high interest because of their high nutritional quality and multiple health benefits, but they are currently undervalued due to their limited solubility and stability. Glycated patatin (PTT) with galactose, galactooligosaccharides (GOSs) and galactan were produced through the Maillard reaction and characterised structurally and functionally. Fourier-transform infrared and fluorescence spectroscopy data revealed important changes in total secondary structures through glycation with GOSs (61.2%) and galactan (36.7%) and also significant tertiary structural changes leading to an exposure of tryptophan residues. These structural changes led to more heat stable forms of PTT with a higher unfolding temperature (70-90 °C) than the unmodified protein (50-70 °C) and with higher antioxidant activity. PTT:galactose conjugates exhibited similar thermal stability and pH-structural behaviour to native PTT. However, the high level of galactose conjugation to PTT and increased exposure of hydrophobic residues led to a significant increase in its emulsifying stability at pH 3.

Research paper thumbnail of Glycation of lysozyme with galactose, galactooligosaccharides and potato galactan through the Maillard reaction and optimization of the production of prebiotic glycoproteins

Process Biochemistry, 2012

The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and pot... more The production of glycated lysozyme (LZM), with galactose, galactooligosaccharides (GOSs) and potato galactan through the Maillard reaction, was investigated. The percent blocked lysine, estimated from the furosine content, reached a maximum value of 11.2% for LZM:galactan conjugates after 1 day incubation at a a w of 0.65. A maximum percent blocked lysine of 7.0 and 13.5% were obtained for LZM:galactose/GOS conjugates at a lower a w of 0.45 after 3 and 7 days, respectively. However, the low percent blocked lysine and the high protein aggregation index of LZM:galactose/GOS conjugates at a w 0.79 and 0.65 revealed the prevalence of the degradation of the Amadori compounds and the protein cross-linking. Mass spectrometry of LZM conjugates revealed the formation of different glycoforms. Glycated LZMs containing up to seven galactose moieties were formed; while only mono-and diglycated LZMs with GOSs were detected. 2-3 mol of galactan were conjugated to 1 mol of LZM. Response surface methodology, based on a 5-level and 3-factor central composite design, revealed that molar ratio and temperature were the most significant variables for the glycation of LZM with GOSs. The optimal conditions leading to a high percent blocked lysine (16.11%) with a low protein aggregation index (0.11) were identified: temperature of 49.5 • C, LZM:GOS molar ratio of 1:9 and a w of 0.65. To the best of our knowledge, this is the first study on the optimization of LZM glycation with GOSs.

Research paper thumbnail of Article Enzymatic Synthesis of Galactosylated Serine/Threonine Derivatives by β-Galactosidase from Escherichia coli

Abstract: The transgalactosylations of serine/threonine derivatives were investigated using β-gal... more Abstract: The transgalactosylations of serine/threonine derivatives were investigated using β-galactosidase from Escherichia coli as biocatalyst. Using ortho-nitrophenyl-β-D-galactoside as donor, the highest bioconversion yield of transgalactosylated N-carboxy benzyl L-serine benzyl ester (23.2%) was achieved in heptane:buffer medium (70:30), whereas with the lactose, the highest bioconversion yield (3.94%) was obtained in the buffer reaction system. The structures of most abundant galactosylated serine products were characterized by MS/MS. The molecular docking simulation revealed that the binding of serine/threonine derivatives to the enzyme’s active site was stronger (−4.6~−7.9 kcal/mol) than that of the natural acceptor, glucose, and mainly occurred through interactions with aromatic residues. For N-tert-butoxycarbonyl serine methyl ester (6.8%) and N-carboxybenzyl serine benzyl ester (3.4%), their binding affinities and the distances between their hydroxyl side chain and the 1′...

Research paper thumbnail of Biotransformation of sucrose rich Maple syrups into fructooligosaccharides, oligolevans and levans using levansucrase biocatalyst: Bioprocess optimization and prebiotic activity assessment

Research paper thumbnail of Interactions of caseins with phenolic acids found in chocolate

Food Research International, 2015

To investigate the interactions between caseins and phenolic acids, such as the ones present in c... more 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. Minor aggregation of casein isolated from milk chocolate was also observed. In vitro hydrolysis of casein control, casein-protocatechuic acid, casein-p-coumaric acid, caseins isolated from milk chocolate and white chocolate using trypsin showed degree of hydrolysis of 19.3, 18.6, 17.7, 10.4 and 17.8% respectively. The presence of protocatechuic acid and p-coumaric acid in the model system and the presence of phenolic compounds in milk chocolate, in addition to the structural changes occurring during processing, affected the peptide profiles of casein hydrolysates.

Research paper thumbnail of Bacillus amyloliquefaciens levansucrase-catalyzed the synthesis of fructooligosaccharides, oligolevan and levan in maple syrup-based reaction systems

Carbohydrate Polymers, 2015

Maple syrups with selected degree Brix (°Bx) (15, 30, 60) were investigated as reaction systems f... more Maple syrups with selected degree Brix (°Bx) (15, 30, 60) were investigated as reaction systems for levansucrase from Bacillus amyloliquefaciens. The enzymatic conversion of sucrose present in the maple syrup and the production of the transfructosylation products were assessed over a time course of 48h. At 30°C, the use of maple syrup 30°Bx led to the highest levansucrase activity (427.53μmol/mg protein/min), while maple syrup 66°Bx led to the highest converted sucrose concentration (1.53M). In maple syrup 30°Bx, oligolevans (10<DP≤30) were synthesized as major products (>80%). In maple syrup 66°Bx, the most abundant products were oligolevans at 30°C and levans (DP≥30) at 8°C. The acceptor specificity study revealed the ability of B. amyloliquefaciens levansucrase to synthesize a variety of hetero-fructooligosaccharides (FOSs) in maple syrups 15°Bx and 30°Bx enriched with various disaccharides, with lactose being the preferred fructosyl acceptor. The current study is the first to investigate maple-syrup-based reaction systems for the synthesis of FOSs/oligolevans/levans.